Publications by Department of Mesoscopic Physics

Departments of ISQI | Publications of ISQI

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2025
75.	Csanád Hajdú, Cătălin Paşcu Moca, Balázs Dóra, Ireneusz Weymann, Gergely Zaránd Kondo compensation in a pseudogap phase: A renormalization group study Phys. Rev. B, 111 , pp. 155125, 2025. Abstract \| Links \| BibTeX @article{Hajdú2025, title = {Kondo compensation in a pseudogap phase: A renormalization group study}, author = {Csanád Hajdú and Cătălin Paşcu Moca and Balázs Dóra and Ireneusz Weymann and Gergely Zaránd}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.111.155125}, doi = {10.1103/PhysRevB.111.155125}, year = {2025}, date = {2025-04-15}, journal = {Phys. Rev. B}, volume = {111}, pages = {155125}, abstract = {We investigate the critical behavior of the Kondo compensation in the presence of a power-law pseudogap in the density of states, 𝜌⁡(𝜔)∼\|𝜔\|𝜀. For 𝜀<1, generically—in the absence of particle-hole symmetry—this model exhibits a quantum phase transition from a partially screened doublet ground state to a fully screened many-body ground state upon increasing the exchange coupling 𝑗. At the critical point 𝑗c, the Kondo compensation is found to scale as 𝜅⁡(𝑗<𝑗c)=1−𝑔⁡(𝑗) with the local 𝑔-factor vanishing as 𝑔∼\|𝑗−⁢𝑗c\|^𝛽. We combine the perturbative drone fermion method with the nonperturbative numerical renormalization group computations to determine the critical exponent 𝛽⁡(𝜀), which exhibits a nonmonotonous behavior as a function of 𝜀. Our results confirm that the Kondo cloud builds up continuously in the presence of a weak pseudogap as one approaches the phase transition.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We investigate the critical behavior of the Kondo compensation in the presence of a power-law pseudogap in the density of states, 𝜌⁡(𝜔)∼\|𝜔\|𝜀. For 𝜀<1, generically—in the absence of particle-hole symmetry—this model exhibits a quantum phase transition from a partially screened doublet ground state to a fully screened many-body ground state upon increasing the exchange coupling 𝑗. At the critical point 𝑗c, the Kondo compensation is found to scale as 𝜅⁡(𝑗<𝑗c)=1−𝑔⁡(𝑗) with the local 𝑔-factor vanishing as 𝑔∼\|𝑗−⁢𝑗c\|^𝛽. We combine the perturbative drone fermion method with the nonperturbative numerical renormalization group computations to determine the critical exponent 𝛽⁡(𝜀), which exhibits a nonmonotonous behavior as a function of 𝜀. Our results confirm that the Kondo cloud builds up continuously in the presence of a weak pseudogap as one approaches the phase transition. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.111.155125 doi:10.1103/PhysRevB.111.155125 Close
74.	Sylwia Kudła, Vitalii K. Dugaev, Józef Barnaś, Anna Dyrdał Longitudinal magnetoresistance in graphene with random Rashba spin-orbit interaction Phys. Rev. B, 111 , pp. 075413, 2025. Links \| BibTeX @article{Kudla2025, title = {Longitudinal magnetoresistance in graphene with random Rashba spin-orbit interaction}, author = {Sylwia Kudła and Vitalii K. Dugaev and Józef Barnaś and Anna Dyrdał}, url = {https://link.aps.org/doi/10.1103/PhysRevB.111.075413}, doi = {10.1103/PhysRevB.111.075413}, year = {2025}, date = {2025-02-11}, journal = {Phys. Rev. B}, volume = {111}, pages = {075413}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close https://link.aps.org/doi/10.1103/PhysRevB.111.075413 doi:10.1103/PhysRevB.111.075413 Close
73.	Piotr Trocha Spin-dependent thermoelectric properties of a hybrid ferromagnetic metal/quantum dot/topological insulator junction Scientific Reports, 15 (4904), 2025. Abstract \| Links \| BibTeX @article{Trocha2025, title = {Spin-dependent thermoelectric properties of a hybrid ferromagnetic metal/quantum dot/topological insulator junction}, author = {Piotr Trocha}, url = {https://www.nature.com/articles/s41598-025-87931-7}, doi = {10.1038/s41598-025-87931-7}, year = {2025}, date = {2025-02-10}, journal = {Scientific Reports}, volume = {15}, number = {4904}, abstract = {The thermoelectric properties of hybrid system based on a single-level quantum dot coupled to a ferromagnetic metallic lead and attached to the surface states of a three-dimensional topological insulator are theoretically investigated. On the surface of a three-dimensional topological insulator, massless helical Dirac fermions emerge. We calculate the thermoelectric coefficients, including electrical conductance, Seebeck coefficient (thermopower), heat conductance, and the figure of merit, using the nonequilibrium Green’s function technique. The results are analyzed in terms of the emergence of new effects. The calculations are performed within the Hubbard I approximation concerning the dot’s Coulomb interactions. Additionally, the spin-dependent coupling of the quantum dot to the ferromagnetic lead lifts the spin degeneracy of the dot’s level, which influences the transport properties of the system. We incorporate this effect perturbatively to obtain the spin-dependent renormalization of the dot’s level. We also consider the case of finite spin accumulation in the ferromagnetic electrode, which leads to spin thermoelectric effects.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close The thermoelectric properties of hybrid system based on a single-level quantum dot coupled to a ferromagnetic metallic lead and attached to the surface states of a three-dimensional topological insulator are theoretically investigated. On the surface of a three-dimensional topological insulator, massless helical Dirac fermions emerge. We calculate the thermoelectric coefficients, including electrical conductance, Seebeck coefficient (thermopower), heat conductance, and the figure of merit, using the nonequilibrium Green’s function technique. The results are analyzed in terms of the emergence of new effects. The calculations are performed within the Hubbard I approximation concerning the dot’s Coulomb interactions. Additionally, the spin-dependent coupling of the quantum dot to the ferromagnetic lead lifts the spin degeneracy of the dot’s level, which influences the transport properties of the system. We incorporate this effect perturbatively to obtain the spin-dependent renormalization of the dot’s level. We also consider the case of finite spin accumulation in the ferromagnetic electrode, which leads to spin thermoelectric effects. Close https://www.nature.com/articles/s41598-025-87931-7 doi:10.1038/s41598-025-87931-7 Close
72.	Emil Siuda, Piotr Trocha Thermal Gradient Powering Spin Current in Quantum Dot-Magnetic Insulators Hybrid Journal of Superconductivity and Novel Magnetism, 38 (81), 2025. Abstract \| Links \| BibTeX @article{Siuda2025, title = {Thermal Gradient Powering Spin Current in Quantum Dot-Magnetic Insulators Hybrid}, author = {Emil Siuda and Piotr Trocha }, url = {https://link.springer.com/article/10.1007/s10948-025-06921-y}, doi = {10.1007/s10948-025-06921-y}, year = {2025}, date = {2025-02-07}, journal = {Journal of Superconductivity and Novel Magnetism}, volume = {38}, number = {81}, abstract = {The growing energy consumption of the computational sector worldwide necessitates the search for sustainable methods of powering and performing calculations. The fast-emerging field of spin caloritronics offers a promising solution by combining the advantages of performing computations on spins instead of charges and driving these computations through temperature differences rather than voltage. Among the various approaches, spin waves and their quanta of excitations, known as magnons, are considered promising carriers of spin-encoded information. In this article, we examine the magnon current generated in a system composed of a magnetic insulator/quantum dot/magnetic insulator, driven by a small temperature difference applied between the two insulators. By expanding the magnon current in terms of the applied temperature bias, we analyze the contributions of successive terms up to the third order of the temperature difference. Each term exhibits a similar structure, consisting of a driving-like and a damping-like component. The driving-like term is dependent on the coupling strength between the quantum dot and the electrodes. We explicitly show that the second-order term of the magnon current vanishes when the couplings of the quantum dot to the magnetic insulators are equal. Overall, the first two terms are sufficient to capture the behavior of the magnon current across the full range of temperature differences. For extreme values of the temperature gradient, the approximate results align with the exact ones only when there is significant asymmetry in the coupling strengths. Finally, we demonstrate that the system can function as a spin diode, capable of rectifying the magnon current when the temperature bias is reversed.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close The growing energy consumption of the computational sector worldwide necessitates the search for sustainable methods of powering and performing calculations. The fast-emerging field of spin caloritronics offers a promising solution by combining the advantages of performing computations on spins instead of charges and driving these computations through temperature differences rather than voltage. Among the various approaches, spin waves and their quanta of excitations, known as magnons, are considered promising carriers of spin-encoded information. In this article, we examine the magnon current generated in a system composed of a magnetic insulator/quantum dot/magnetic insulator, driven by a small temperature difference applied between the two insulators. By expanding the magnon current in terms of the applied temperature bias, we analyze the contributions of successive terms up to the third order of the temperature difference. Each term exhibits a similar structure, consisting of a driving-like and a damping-like component. The driving-like term is dependent on the coupling strength between the quantum dot and the electrodes. We explicitly show that the second-order term of the magnon current vanishes when the couplings of the quantum dot to the magnetic insulators are equal. Overall, the first two terms are sufficient to capture the behavior of the magnon current across the full range of temperature differences. For extreme values of the temperature gradient, the approximate results align with the exact ones only when there is significant asymmetry in the coupling strengths. Finally, we demonstrate that the system can function as a spin diode, capable of rectifying the magnon current when the temperature bias is reversed. Close https://link.springer.com/article/10.1007/s10948-025-06921-y doi:10.1007/s10948-025-06921-y Close
71.	Anand Manaparambil, Andreas Weichselbaum, Jan von Delft, Ireneusz Weymann Nonequilibrium steady-state thermoelectrics of Kondo-correlated quantum dots Phys. Rev. B, 111 , pp. 035445, 2025. Abstract \| Links \| BibTeX @article{Manaparambil2025, title = {Nonequilibrium steady-state thermoelectrics of Kondo-correlated quantum dots}, author = {Anand Manaparambil and Andreas Weichselbaum and Jan von Delft and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.111.035445}, doi = {10.1103/PhysRevB.111.035445}, year = {2025}, date = {2025-01-27}, journal = {Phys. Rev. B}, volume = {111}, pages = {035445}, abstract = {The transport across a Kondo-correlated quantum dot coupled to two leads with independent temperatures and chemical potentials is studied using a controlled nonperturbative, and in this sense numerically exact, treatment based on a hybrid numerical renormalization group combined with time-dependent density matrix renormalization group (NRG-tDMRG). In the Kondo regime, for sufficiently large fixed voltage bias 𝑉≳𝑇𝐾, with 𝑇𝐾 the Kondo temperature, we find a peak in the conductance vs the temperature gradient Δ⁢𝑇=𝑇𝑅−𝑇𝐿 across left and right lead. Focusing then on zero voltage bias but finite Δ⁢𝑇 far beyond linear response, we reveal the dependence of the characteristic zero-bias conductance on the individual lead temperatures. We find that the finite-Δ⁢𝑇 data behaves quantitatively similar to linear response with an effective equilibrium temperature derived from the different lead temperatures. The regime of sign changes in the Seebeck coefficient, signaling the presence of Kondo correlations, and its dependence on the individual lead temperatures provide a complete picture of the Kondo regime in the presence of finite-temperature gradients. The results from the zero-bias conductance and Seebeck coefficient studies unveil an approximate “Kondo circle” in the 𝑇𝐿/𝑇𝑅 plane as the regime within which the Kondo correlations dominate. We also study the heat current and the corresponding heat conductance vs finite Δ⁢𝑇. We provide a polynomial fit for our numerical results for the thermocurrent as a function of the individual lead temperatures, which may be used to fit experimental data in the Kondo regime.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close The transport across a Kondo-correlated quantum dot coupled to two leads with independent temperatures and chemical potentials is studied using a controlled nonperturbative, and in this sense numerically exact, treatment based on a hybrid numerical renormalization group combined with time-dependent density matrix renormalization group (NRG-tDMRG). In the Kondo regime, for sufficiently large fixed voltage bias 𝑉≳𝑇𝐾, with 𝑇𝐾 the Kondo temperature, we find a peak in the conductance vs the temperature gradient Δ⁢𝑇=𝑇𝑅−𝑇𝐿 across left and right lead. Focusing then on zero voltage bias but finite Δ⁢𝑇 far beyond linear response, we reveal the dependence of the characteristic zero-bias conductance on the individual lead temperatures. We find that the finite-Δ⁢𝑇 data behaves quantitatively similar to linear response with an effective equilibrium temperature derived from the different lead temperatures. The regime of sign changes in the Seebeck coefficient, signaling the presence of Kondo correlations, and its dependence on the individual lead temperatures provide a complete picture of the Kondo regime in the presence of finite-temperature gradients. The results from the zero-bias conductance and Seebeck coefficient studies unveil an approximate “Kondo circle” in the 𝑇𝐿/𝑇𝑅 plane as the regime within which the Kondo correlations dominate. We also study the heat current and the corresponding heat conductance vs finite Δ⁢𝑇. We provide a polynomial fit for our numerical results for the thermocurrent as a function of the individual lead temperatures, which may be used to fit experimental data in the Kondo regime. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.111.035445 doi:10.1103/PhysRevB.111.035445 Close
70.	Piotr Trocha, Thibaut Jonckheere, Jérôme Rech, Thierry Martin Thermoelectric properties of a quantum dot attached to normal metal and topological superconductor Scientific Reports, 15 (3068), 2025. Abstract \| Links \| BibTeX @article{Trocha2025b, title = {Thermoelectric properties of a quantum dot attached to normal metal and topological superconductor}, author = {Piotr Trocha and Thibaut Jonckheere and Jérôme Rech and Thierry Martin}, url = {https://www.nature.com/articles/s41598-024-84770-w}, doi = {10.1038/s41598-024-84770-w}, year = {2025}, date = {2025-01-24}, journal = {Scientific Reports}, volume = {15}, number = {3068}, abstract = {The thermoelectric properties of hybrid systems based on a single-level quantum dot coupled to a normal-metal/half-metallic lead and attached to a topological superconductor wire are investigated. The topological superconductor wire is modeled by a spinless p-wave superconductor which hosts both a Majorana bound state at its extremity and above gap quasiparticle excitations. The main interest of our investigation is to study the interplay of sub-gap and single-particle tunneling processes and their contributions to the thermoelectric response of the considered system. The above gap tunneling driven by a temperature gradient is responsible for relatively large thermopower, whereas sub-gap processes only indirectly influence the thermoelectric response. The thermoelectric coefficients, including electric conductance, Seebeck coefficient (thermopower), heat conductance, and figure of merit, are calculated by means of the non-equilibrium Green’s function technique and the temperature dependence of the superconducting gap is considered within the BCS theory. We also consider the system out of equilibrium working as a heat engine. The output power and the corresponding efficiency are presented. Interestingly, under certain conditions, it is possible to extract more power in the superconducting phase than in the normal phase, with comparable efficiency.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close The thermoelectric properties of hybrid systems based on a single-level quantum dot coupled to a normal-metal/half-metallic lead and attached to a topological superconductor wire are investigated. The topological superconductor wire is modeled by a spinless p-wave superconductor which hosts both a Majorana bound state at its extremity and above gap quasiparticle excitations. The main interest of our investigation is to study the interplay of sub-gap and single-particle tunneling processes and their contributions to the thermoelectric response of the considered system. The above gap tunneling driven by a temperature gradient is responsible for relatively large thermopower, whereas sub-gap processes only indirectly influence the thermoelectric response. The thermoelectric coefficients, including electric conductance, Seebeck coefficient (thermopower), heat conductance, and figure of merit, are calculated by means of the non-equilibrium Green’s function technique and the temperature dependence of the superconducting gap is considered within the BCS theory. We also consider the system out of equilibrium working as a heat engine. The output power and the corresponding efficiency are presented. Interestingly, under certain conditions, it is possible to extract more power in the superconducting phase than in the normal phase, with comparable efficiency. Close https://www.nature.com/articles/s41598-024-84770-w doi:10.1038/s41598-024-84770-w Close
2024
69.	Anna Krzyżewska, Anna Dyrdał Nonlinear Hall Effect in Isotropic k-Cubed Rashba Model: Berry-Curvature-Dipole Engineering by In-Plane Magnetic Field physica status solidi (RRL) – Rapid Research Letters, 18 (12), pp. 2400123, 2024, ISSN: 1862-6254. Abstract \| Links \| BibTeX @article{Krzyzewska2024Jun, title = {Nonlinear Hall Effect in Isotropic k-Cubed Rashba Model: Berry-Curvature-Dipole Engineering by In-Plane Magnetic Field}, author = {Anna Krzyżewska and Anna Dyrdał}, url = {https://onlinelibrary.wiley.com/doi/10.1002/pssr.202400123 https://arxiv.org/abs/2404.07352}, doi = {10.1002/pssr.202400123}, issn = {1862-6254}, year = {2024}, date = {2024-12-03}, journal = {physica status solidi (RRL) – Rapid Research Letters}, volume = {18}, number = {12}, pages = {2400123}, abstract = {The linear and nonlinear Hall effects in 2D electron gas are considered theoretically within the isotropic k-cubed Rashba model. It is shown that the presence of an out-of-plane external magnetic field or net magnetization is a necessary condition to induce a nonzero Berry curvature in the system, whereas an in-plane magnetic field tunes the Berry curvature leading to the Berry curvature dipole. Interestingly, in the linear response regime, the conductivity is dominated by the intrinsic component (Berry curvature component), whereas the second-order correction to the Hall current (i.e., the conductivity proportional to the external electric field) is dominated by the component independent of the Berry curvature dipole.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close The linear and nonlinear Hall effects in 2D electron gas are considered theoretically within the isotropic k-cubed Rashba model. It is shown that the presence of an out-of-plane external magnetic field or net magnetization is a necessary condition to induce a nonzero Berry curvature in the system, whereas an in-plane magnetic field tunes the Berry curvature leading to the Berry curvature dipole. Interestingly, in the linear response regime, the conductivity is dominated by the intrinsic component (Berry curvature component), whereas the second-order correction to the Hall current (i.e., the conductivity proportional to the external electric field) is dominated by the component independent of the Berry curvature dipole. Close https://onlinelibrary.wiley.com/doi/10.1002/pssr.202400123 https://arxiv.org/abs/2404.07352 doi:10.1002/pssr.202400123 Close
68.	Stefan Stagraczyński, Pavel Baláž, Mirali Jafari, Józef Barnaś, Anna Dyrdał Magnetic ordering and dynamics in monolayers and bilayers of chromium trihalides: atomistic simulations approach Scientific Reports, 14 , pp. 25552, 2024. Abstract \| Links \| BibTeX @article{Stagraczynski2024, title = {Magnetic ordering and dynamics in monolayers and bilayers of chromium trihalides: atomistic simulations approach}, author = {Stefan Stagraczyński and Pavel Baláž and Mirali Jafari and Józef Barnaś and Anna Dyrdał}, url = {https://doi.org/10.1038/s41598-024-75501-2}, doi = {10.1038/s41598-024-75501-2}, year = {2024}, date = {2024-10-26}, journal = {Scientific Reports}, volume = {14}, pages = {25552}, abstract = {We analyze magnetic properties of monolayers and bilayers of chromium iodide, CrI3, in two different stacking configurations: AA and rhombohedral ones. Our main focus is on the corresponding Curie temperatures, hysteresis curves, equilibrium spin structures, and spin wave excitations. To obtain all these magnetic characteristic, we employ the atomistic spin dynamics and Monte Carlo simulation techniques. The model Hamiltonian includes isotropic exchange coupling, magnetic anisotropy, and Dzyaloshinskii-Moriya interaction. As the latter interaction is relatively weak in pristine CrI3, we consider a more general case, when the Dzyaloshinskii-Moriya interaction is enhanced externally (e.g. due to gate voltage, mechanical strain, or proximity effects). An important issue of the analysis is the correlation between hysteresis curves and spin configurations in the system, as well as formation of the skyrmion textures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We analyze magnetic properties of monolayers and bilayers of chromium iodide, CrI3, in two different stacking configurations: AA and rhombohedral ones. Our main focus is on the corresponding Curie temperatures, hysteresis curves, equilibrium spin structures, and spin wave excitations. To obtain all these magnetic characteristic, we employ the atomistic spin dynamics and Monte Carlo simulation techniques. The model Hamiltonian includes isotropic exchange coupling, magnetic anisotropy, and Dzyaloshinskii-Moriya interaction. As the latter interaction is relatively weak in pristine CrI3, we consider a more general case, when the Dzyaloshinskii-Moriya interaction is enhanced externally (e.g. due to gate voltage, mechanical strain, or proximity effects). An important issue of the analysis is the correlation between hysteresis curves and spin configurations in the system, as well as formation of the skyrmion textures. Close https://doi.org/10.1038/s41598-024-75501-2 doi:10.1038/s41598-024-75501-2 Close
67.	Izabella Wojciechowska, Anna Dyrdał Intrinsic anomalous, spin and valley Hall effects in ’ex-so-tic’ van-der-Waals structures Scientific Reports, 14 , pp. 23808, 2024. Abstract \| Links \| BibTeX @article{Wojciechowska2024, title = {Intrinsic anomalous, spin and valley Hall effects in ’ex-so-tic’ van-der-Waals structures}, author = {Izabella Wojciechowska and Anna Dyrdał }, url = {https://doi.org/10.1038/s41598-024-74596-x}, doi = {10.1038/s41598-024-74596-x}, year = {2024}, date = {2024-10-11}, journal = {Scientific Reports}, volume = {14}, pages = {23808}, abstract = {We consider the anomalous, spin, valley, and valley spin Hall effects in a pristine graphene-based van-der-Waals (vdW) heterostructure consisting of a bilayer graphene (BLG) sandwiched between a semiconducting van-der-Waals material with strong spin-orbit coupling (e.g., WS2) and a ferromagnetic insulating vdW material (e.g. Cr2Ge2Te2). Due to the exchange proximity effect from one side and spin-orbit proximity effect from the other side of graphene, such a structure is referred to as graphene based ’ex-so-tic’ structure. First, we derive an effective Hamiltonian describing the low-energy states of the structure. Then, using the Green’s function formalism, we obtain analytical results for the Hall conductivities as a function of the Fermi energy and gate voltage. For specific values of these parameters, we find a quantized valley Hall conductivity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We consider the anomalous, spin, valley, and valley spin Hall effects in a pristine graphene-based van-der-Waals (vdW) heterostructure consisting of a bilayer graphene (BLG) sandwiched between a semiconducting van-der-Waals material with strong spin-orbit coupling (e.g., WS2) and a ferromagnetic insulating vdW material (e.g. Cr2Ge2Te2). Due to the exchange proximity effect from one side and spin-orbit proximity effect from the other side of graphene, such a structure is referred to as graphene based ’ex-so-tic’ structure. First, we derive an effective Hamiltonian describing the low-energy states of the structure. Then, using the Green’s function formalism, we obtain analytical results for the Hall conductivities as a function of the Fermi energy and gate voltage. For specific values of these parameters, we find a quantized valley Hall conductivity. Close https://doi.org/10.1038/s41598-024-74596-x doi:10.1038/s41598-024-74596-x Close
66.	Peter Zalom, Kacper Wrześniewski, Tomáš Novotný, Ireneusz Weymann Double quantum dot Andreev molecules: Phase diagrams and critical evaluation of effective models Physical Review B, 110 , pp. 134506, 2024. Abstract \| Links \| BibTeX @article{Zalom2024, title = {Double quantum dot Andreev molecules: Phase diagrams and critical evaluation of effective models}, author = {Peter Zalom and Kacper Wrześniewski and Tomáš Novotný and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.110.134506}, doi = {10.1103/PhysRevB.110.134506}, year = {2024}, date = {2024-10-07}, journal = {Physical Review B}, volume = {110}, pages = {134506}, abstract = {This paper systematically investigates the phase diagram of a parallel double-quantum-dot Andreev molecule, where the two quantum dots are coupled to a common superconducting lead. Using the numerical renormalization group method, we map out the evolution of the ground state across a wide parameter space of level detunings, size of the superconducting gap, lead couplings, and interdot coupling strength. The intricate phase diagrams feature singlet, doublet, and a relatively uncommon triplet ground states, with the latter being a distinct signature of strong lead-mediated interactions between the quantum dots. We benchmark the applicability of simplified effective models, including the atomic limit and zero-bandwidth approximations, in capturing the complex behavior of this parallel configuration. Our analysis reveals severe limitations of these models, underscoring the necessity for maximal caution when extrapolating beyond their tested validity. In particular, all effective models except for the extended version of the zero-bandwidth approximation failed in reproducing the triplet ground state and made several false predictions. These findings provide crucial insights for interpreting experimental observations and designing superconducting devices based on quantum-dot architectures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close This paper systematically investigates the phase diagram of a parallel double-quantum-dot Andreev molecule, where the two quantum dots are coupled to a common superconducting lead. Using the numerical renormalization group method, we map out the evolution of the ground state across a wide parameter space of level detunings, size of the superconducting gap, lead couplings, and interdot coupling strength. The intricate phase diagrams feature singlet, doublet, and a relatively uncommon triplet ground states, with the latter being a distinct signature of strong lead-mediated interactions between the quantum dots. We benchmark the applicability of simplified effective models, including the atomic limit and zero-bandwidth approximations, in capturing the complex behavior of this parallel configuration. Our analysis reveals severe limitations of these models, underscoring the necessity for maximal caution when extrapolating beyond their tested validity. In particular, all effective models except for the extended version of the zero-bandwidth approximation failed in reproducing the triplet ground state and made several false predictions. These findings provide crucial insights for interpreting experimental observations and designing superconducting devices based on quantum-dot architectures. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.110.134506 doi:10.1103/PhysRevB.110.134506 Close
65.	Wojciech Rudziński, Józef Barnaś, Anna Dyrdał Spin waves in antiferromagnetically coupled bilayers of transition-metal dichalcogenides with Dzyaloshinskii–Moriya interaction Journal of Magnetism and Magnetic Materials, 606 , pp. 172321, 2024. Abstract \| Links \| BibTeX @article{Rudzinski2024b, title = {Spin waves in antiferromagnetically coupled bilayers of transition-metal dichalcogenides with Dzyaloshinskii–Moriya interaction}, author = {Wojciech Rudziński and Józef Barnaś and Anna Dyrdał}, url = {https://doi.org/10.1016/j.jmmm.2024.172321}, doi = {10.1016/j.jmmm.2024.172321}, year = {2024}, date = {2024-09-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {606}, pages = {172321}, abstract = {In this paper we analyse quantized spin waves (also referred to as magnons) in bilayers of two-dimensional van der Waals materials, like Vanadium-based dichalcogenides, VX2 (X = S, Se, Te) and other materials of similar symmetry. We assume that the materials exhibit Dzyaloshinskii–Moriya interaction and in-plane easy-axis magnetic anisotropy due to symmetry breaking induced externally (e.g. by strain, gate voltage, proximity effects to an appropriate substrate/oberlayer, etc.). The considerations are limited to a collinear spin ground state, stabilized by a sufficiently strong in-plane magnetic anisotropy. The theoretical analysis is performed within the general spin wave theory based on the Holstein–Primakoff–Bogoliubov transformation. Accordingly, the description takes into account quantum antiferromagnetic fluctuations. However, it is limited to linear spinwave modes. The Dzyaloshinskii–Moriya interaction is shown to modify the spin wave spectrum of the bilayers, making its low energy part qualitatively similar to the electronic spectrum of the Rashba spin–orbit model.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close In this paper we analyse quantized spin waves (also referred to as magnons) in bilayers of two-dimensional van der Waals materials, like Vanadium-based dichalcogenides, VX2 (X = S, Se, Te) and other materials of similar symmetry. We assume that the materials exhibit Dzyaloshinskii–Moriya interaction and in-plane easy-axis magnetic anisotropy due to symmetry breaking induced externally (e.g. by strain, gate voltage, proximity effects to an appropriate substrate/oberlayer, etc.). The considerations are limited to a collinear spin ground state, stabilized by a sufficiently strong in-plane magnetic anisotropy. The theoretical analysis is performed within the general spin wave theory based on the Holstein–Primakoff–Bogoliubov transformation. Accordingly, the description takes into account quantum antiferromagnetic fluctuations. However, it is limited to linear spinwave modes. The Dzyaloshinskii–Moriya interaction is shown to modify the spin wave spectrum of the bilayers, making its low energy part qualitatively similar to the electronic spectrum of the Rashba spin–orbit model. Close https://doi.org/10.1016/j.jmmm.2024.172321 doi:10.1016/j.jmmm.2024.172321 Close
64.	Amir N. Zarezad, Alireza Qaiumzadeh, Józef Barnaś, Anna Dyrdał Topological charge and spin Hall effects due to skyrmions in canted antiferromagnets Physical Review B, 110 (5), pp. 054431, 2024. Abstract \| Links \| BibTeX @article{Zarezad2024b, title = {Topological charge and spin Hall effects due to skyrmions in canted antiferromagnets}, author = {Amir N. Zarezad and Alireza Qaiumzadeh and Józef Barnaś and Anna Dyrdał }, url = {https://doi.org/10.1103/PhysRevB.110.054431}, doi = {10.1103/PhysRevB.110.054431}, year = {2024}, date = {2024-08-20}, journal = {Physical Review B}, volume = {110}, number = {5}, pages = {054431}, abstract = {The topological charge Hall effect (TCHE) and the topological spin Hall effect (TSHE), arising from ferromagnetic (FM) and antiferromagnetic (AFM) skyrmions, respectively, can be elucidated through the emergence of spin-dependent Berry gauge fields that affect the adiabatic flow of electrons within the skyrmion texture. TCHE is absent in systems with parity-time (PT) symmetry, such as collinear AFM systems. In this paper, we theoretically study TCHE and TSHE in a canted antiferromagnet within the diffusive transport regime. Spin canting or weak ferromagnetism in canted AFMs, which break the PT symmetry, may arise, e.g., from strong homogeneous Dzyaloshinskii-Moriya interactions. Using a semiclassical Boltzmann approach, we obtain diffusion equations for the spin and charge accumulations in the presence of finite spin flip and spin-dependent momentum relaxation times. We show that the weak ferromagnetic moment stemming from spin canting and the subsequent breaking of PT symmetry, results in the emergence of both finite TCHE and TSHE in AFM systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close The topological charge Hall effect (TCHE) and the topological spin Hall effect (TSHE), arising from ferromagnetic (FM) and antiferromagnetic (AFM) skyrmions, respectively, can be elucidated through the emergence of spin-dependent Berry gauge fields that affect the adiabatic flow of electrons within the skyrmion texture. TCHE is absent in systems with parity-time (PT) symmetry, such as collinear AFM systems. In this paper, we theoretically study TCHE and TSHE in a canted antiferromagnet within the diffusive transport regime. Spin canting or weak ferromagnetism in canted AFMs, which break the PT symmetry, may arise, e.g., from strong homogeneous Dzyaloshinskii-Moriya interactions. Using a semiclassical Boltzmann approach, we obtain diffusion equations for the spin and charge accumulations in the presence of finite spin flip and spin-dependent momentum relaxation times. We show that the weak ferromagnetic moment stemming from spin canting and the subsequent breaking of PT symmetry, results in the emergence of both finite TCHE and TSHE in AFM systems. Close https://doi.org/10.1103/PhysRevB.110.054431 doi:10.1103/PhysRevB.110.054431 Close
63.	Piotr Majek, Ireneusz Weymann Spin-selective transport in a correlated double quantum dot-Majorana wire system Scientific Reports, 14 , pp. 17762, 2024. Abstract \| Links \| BibTeX @article{Majek2024b, title = {Spin-selective transport in a correlated double quantum dot-Majorana wire system}, author = {Piotr Majek and Ireneusz Weymann}, url = {https://www.nature.com/articles/s41598-024-66478-z}, doi = {10.1038/s41598-024-66478-z}, year = {2024}, date = {2024-08-01}, journal = {Scientific Reports}, volume = {14}, pages = {17762}, abstract = {In this work we investigate the spin-dependent transport through a double quantum dot embedded in a ferromagnetic tunnel junction and side attached to a topological superconducting nanowire hosting Majorana zero-energy modes. We focus on the transport regime when the Majorana mode leaks into the double quantum dot competing with the two-stage Kondo effect and the ferromagnetic-contact-induced exchange field. In particular, we determine the system’s spectral properties and analyze the temperature dependence of the spin-resolved linear conductance by means of the numerical renormalization group method. Our study reveals unique signatures of the interplay between the spin-resolved tunneling, the Kondo effect and the Majorana modes, which are visible in the transport characteristics. In particular, we uncover a competing character of the coupling to topological superconductor and that to ferromagnetic leads, which can be observed already for very low spin polarization of the electrodes. This is signaled by an almost complete quenching of the conductance in one of the spin channels which is revealed through perfect conductance spin polarization. Moreover, we show that the conductance spin polarization can change sign depending on the magnitude of spin imbalance in the leads and strength of interaction with topological wire. Thus, our work demonstrates that even minuscule spin polarization of tunneling processes can have large impact on the transport properties of the system.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close In this work we investigate the spin-dependent transport through a double quantum dot embedded in a ferromagnetic tunnel junction and side attached to a topological superconducting nanowire hosting Majorana zero-energy modes. We focus on the transport regime when the Majorana mode leaks into the double quantum dot competing with the two-stage Kondo effect and the ferromagnetic-contact-induced exchange field. In particular, we determine the system’s spectral properties and analyze the temperature dependence of the spin-resolved linear conductance by means of the numerical renormalization group method. Our study reveals unique signatures of the interplay between the spin-resolved tunneling, the Kondo effect and the Majorana modes, which are visible in the transport characteristics. In particular, we uncover a competing character of the coupling to topological superconductor and that to ferromagnetic leads, which can be observed already for very low spin polarization of the electrodes. This is signaled by an almost complete quenching of the conductance in one of the spin channels which is revealed through perfect conductance spin polarization. Moreover, we show that the conductance spin polarization can change sign depending on the magnitude of spin imbalance in the leads and strength of interaction with topological wire. Thus, our work demonstrates that even minuscule spin polarization of tunneling processes can have large impact on the transport properties of the system. Close https://www.nature.com/articles/s41598-024-66478-z doi:10.1038/s41598-024-66478-z Close
62.	Ryszard Taranko, Kacper Wrześniewski, Ireneusz Weymann, Tadeusz Domański Transient effects in quantum dots contacted via topological superconductor Physical Review B, 110 , pp. 035413, 2024. Abstract \| Links \| BibTeX @article{Taranko2024, title = {Transient effects in quantum dots contacted via topological superconductor}, author = {Ryszard Taranko and Kacper Wrześniewski and Ireneusz Weymann and Tadeusz Domański}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.110.035413}, doi = {10.1103/PhysRevB.110.035413}, year = {2024}, date = {2024-07-10}, journal = {Physical Review B}, volume = {110}, pages = {035413}, abstract = {We investigate gradual development of the quasiparticle states in two quantum dots attached to opposite sides of the topological superconducting nanowire, hosting the boundary modes. Specifically, we explore the nonequilibrium cross-correlations transmitted between these quantum dots via the zero-energy Majorana modes. Our analytical and numerical results reveal the nonlocal features observable in the transient behavior of electron pairing, which subsequently cease while the hybrid structure evolves towards its asymptotic steady-state configuration. We estimate duration of these temporary phenomena. Using the nonperturbative scheme of the time-dependent numerical renormalization group technique we also analyze nonequilibrium signatures of the correlation effects competing with the proximity induced electron pairing. These dynamical processes could manifest themselves in braiding protocols imposed on the topological and/or conventional superconducting quantum bits, using superconducting hybrid nanostructures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We investigate gradual development of the quasiparticle states in two quantum dots attached to opposite sides of the topological superconducting nanowire, hosting the boundary modes. Specifically, we explore the nonequilibrium cross-correlations transmitted between these quantum dots via the zero-energy Majorana modes. Our analytical and numerical results reveal the nonlocal features observable in the transient behavior of electron pairing, which subsequently cease while the hybrid structure evolves towards its asymptotic steady-state configuration. We estimate duration of these temporary phenomena. Using the nonperturbative scheme of the time-dependent numerical renormalization group technique we also analyze nonequilibrium signatures of the correlation effects competing with the proximity induced electron pairing. These dynamical processes could manifest themselves in braiding protocols imposed on the topological and/or conventional superconducting quantum bits, using superconducting hybrid nanostructures. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.110.035413 doi:10.1103/PhysRevB.110.035413 Close
61.	Grzegorz Górski, Krzysztof Paweł Wójcik, Jan Barański, Ireneusz Weymann, Tadeusz Domański Nonlocal correlations transmitted between quantum dots via short topological superconductor Scientific Reports, 13 , pp. 13848, 2024. Abstract \| Links \| BibTeX @article{Górski2024, title = {Nonlocal correlations transmitted between quantum dots via short topological superconductor}, author = {Grzegorz Górski and Krzysztof Paweł Wójcik and Jan Barański and Ireneusz Weymann and Tadeusz Domański }, url = {https://www.nature.com/articles/s41598-024-64578-4}, doi = {10.1038/s41598-024-64578-4}, year = {2024}, date = {2024-06-15}, journal = {Scientific Reports}, volume = {13}, pages = {13848}, abstract = {We study the quasiparticle states and nonlocal correlations of a hybrid structure, comprising two quantum dots interconnected through a short-length topological superconducting nanowire hosting overlaping Majorana modes. We show that the hybridization between different components of this setup gives rise to the emergence of molecular states, which are responsible for nonlocal correlations. We inspect the resulting energy structure, focusing on the inter-dependence between the quasiparticles of individual quantum dots. We predict the existence of nonlocal effects, which could be accessed and probed by crossed Andreev reflection spectroscopy. Our study would be relevant to a recent experimental realization of the minimal Kitaev model [T. Dvir et al., Nature 614, 445 (2023)], by considering its hybrid structure with side-attached quantum dots.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We study the quasiparticle states and nonlocal correlations of a hybrid structure, comprising two quantum dots interconnected through a short-length topological superconducting nanowire hosting overlaping Majorana modes. We show that the hybridization between different components of this setup gives rise to the emergence of molecular states, which are responsible for nonlocal correlations. We inspect the resulting energy structure, focusing on the inter-dependence between the quasiparticles of individual quantum dots. We predict the existence of nonlocal effects, which could be accessed and probed by crossed Andreev reflection spectroscopy. Our study would be relevant to a recent experimental realization of the minimal Kitaev model [T. Dvir et al., Nature 614, 445 (2023)], by considering its hybrid structure with side-attached quantum dots. Close https://www.nature.com/articles/s41598-024-64578-4 doi:10.1038/s41598-024-64578-4 Close
60.	Verena Brehm, Stefan Stagraczyński, Józef Barnaś, Anna Dyrdał, Alireza Qaiumzadeh Magnon dispersion and spin transport in CrCl3 bilayers under different strain-induced magnetic states Physical Review Materials, 8 (5), pp. 054002, 2024. Abstract \| Links \| BibTeX @article{Brehm2024, title = {Magnon dispersion and spin transport in CrCl3 bilayers under different strain-induced magnetic states}, author = {Verena Brehm and Stefan Stagraczyński and Józef Barnaś and Anna Dyrdał and Alireza Qaiumzadeh}, url = {https://doi.org/10.1103/PhysRevMaterials.8.054002 }, doi = {10.1103/PhysRevMaterials.8.054002}, year = {2024}, date = {2024-05-03}, journal = {Physical Review Materials}, volume = {8}, number = {5}, pages = {054002}, abstract = {Atomically thin van der Waals magnetic materials offer exceptional opportunities to mechanically and electrically manipulate magnetic states and spin textures. The possibility of efficient spin transport in these materials makes them promising for the development of novel nanospintronics technology. Using atomistic spin dynamics simulations, we investigate magnetic ground state, magnon dispersion, critical temperature, and magnon spin transport in CrCl3 bilayers in the absence and presence of compressive and tensile strains. We show that in the presence of mechanical strain, the magnon band gap at the Γ point and the critical temperature of the bilayer are increased. Furthermore, our simulations show that the magnon diffusion length is reduced in the presence of strain. Moreover, by exciting magnons through the spin Seebeck effect and spin Hall-induced torque, we illustrate distinctions between magnon spin transport in the antiferromagnetic state, under compressive strains, and ferromagnetic states, under tensile strains or in the unstrained case.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Atomically thin van der Waals magnetic materials offer exceptional opportunities to mechanically and electrically manipulate magnetic states and spin textures. The possibility of efficient spin transport in these materials makes them promising for the development of novel nanospintronics technology. Using atomistic spin dynamics simulations, we investigate magnetic ground state, magnon dispersion, critical temperature, and magnon spin transport in CrCl3 bilayers in the absence and presence of compressive and tensile strains. We show that in the presence of mechanical strain, the magnon band gap at the Γ point and the critical temperature of the bilayer are increased. Furthermore, our simulations show that the magnon diffusion length is reduced in the presence of strain. Moreover, by exciting magnons through the spin Seebeck effect and spin Hall-induced torque, we illustrate distinctions between magnon spin transport in the antiferromagnetic state, under compressive strains, and ferromagnetic states, under tensile strains or in the unstrained case. Close https://doi.org/10.1103/PhysRevMaterials.8.054002 doi:10.1103/PhysRevMaterials.8.054002 Close
59.	Michał Inglot, Józef Barnaś, Vitalii K. Dugaev, Anna Dyrdał Localized states at the Rashba spin-orbit domain wall in magnetized graphene: Interplay of Rashba and magnetic domain walls Physical Review B, 109 (13), pp. 134435, 2024. Abstract \| Links \| BibTeX @article{Inglot2024, title = {Localized states at the Rashba spin-orbit domain wall in magnetized graphene: Interplay of Rashba and magnetic domain walls}, author = {Michał Inglot and Józef Barnaś and Vitalii K. Dugaev and Anna Dyrdał}, url = {https://link.aps.org/doi/10.1103/PhysRevB.109.134435}, doi = {10.1103/PhysRevB.109.134435}, year = {2024}, date = {2024-04-23}, journal = {Physical Review B}, volume = {109}, number = {13}, pages = {134435}, abstract = {It is well known that electronic states in graphene with a uniform Rashba spin-orbit interaction and uniform magnetization, e.g., due to exchange coupling to a magnetic substrate, display an energy gap around the Dirac 𝐾 and 𝐾′ points. When the magnetization of graphene is nonuniform and forms a magnetic domain wall, electronic states localized at the wall emerge in the energy gap. In this paper we show that similar localized electronic states appear in the gap when the graphene is uniformly magnetized, while a domain wall appears in the Rashba spin-orbit interaction (i.e., opposite signs of the Rashba parameter on both sides of the wall). These electronic states propagate along the wall and are localized exponentially at the Rashba domain wall. They form narrow and nearly parabolic (at small wave vectors) bands, with relatively large effective electron mass. However, contrary to the magnetic domain wall, these states do not close the energy gap. We also consider the situation when the magnetic domain wall coexists with the Rashba domain wall, and both walls are localized at the same position. Electronic states due to the interplay of both domain walls are determined analytically and it is shown that the electronic states localized at the walls close the gap when a magnetic domain wall (symmetric or asymmetric) exists, independently of the Rashba parameter behavior.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close It is well known that electronic states in graphene with a uniform Rashba spin-orbit interaction and uniform magnetization, e.g., due to exchange coupling to a magnetic substrate, display an energy gap around the Dirac 𝐾 and 𝐾′ points. When the magnetization of graphene is nonuniform and forms a magnetic domain wall, electronic states localized at the wall emerge in the energy gap. In this paper we show that similar localized electronic states appear in the gap when the graphene is uniformly magnetized, while a domain wall appears in the Rashba spin-orbit interaction (i.e., opposite signs of the Rashba parameter on both sides of the wall). These electronic states propagate along the wall and are localized exponentially at the Rashba domain wall. They form narrow and nearly parabolic (at small wave vectors) bands, with relatively large effective electron mass. However, contrary to the magnetic domain wall, these states do not close the energy gap. We also consider the situation when the magnetic domain wall coexists with the Rashba domain wall, and both walls are localized at the same position. Electronic states due to the interplay of both domain walls are determined analytically and it is shown that the electronic states localized at the walls close the gap when a magnetic domain wall (symmetric or asymmetric) exists, independently of the Rashba parameter behavior. Close https://link.aps.org/doi/10.1103/PhysRevB.109.134435 doi:10.1103/PhysRevB.109.134435 Close
58.	Kateryna Boboshko, Anna Dyrdał Bilinear magnetoresistance and planar Hall effect in topological insulators: Interplay of scattering on spin-orbital impurities and nonequilibrium spin polarization Physical Review B, 109 (15), pp. 155420, 2024. Abstract \| Links \| BibTeX @article{Boboshko2024, title = {Bilinear magnetoresistance and planar Hall effect in topological insulators: Interplay of scattering on spin-orbital impurities and nonequilibrium spin polarization}, author = {Kateryna Boboshko and Anna Dyrdał}, url = {https://link.aps.org/doi/10.1103/PhysRevB.109.155420}, doi = {10.1103/PhysRevB.109.155420}, year = {2024}, date = {2024-04-15}, journal = {Physical Review B}, volume = {109}, number = {15}, pages = {155420}, abstract = {We have considered theoretically nonlinear transport phenomena known as bilinear magnetoresistance (BMR) and nonlinear planar Hall effect (NPHE) within the effective model describing surface states of a 3D topological insulator. Both phenomena can occur in nonmagnetic materials with strong spin-orbit interaction and reveal a term that depends linearly on the charge current density (external electric field) and in-plane magnetic field. In earlier studies, the physical mechanism of BMR and NPHE was related to scattering on spin-momentum locking inhomogeneities or to the hexagonal warping of Dirac cones. Here, we focus on another mechanism related to scattering on impurities that inherently contain spin-orbit coupling. Using the Green's function formalism and diagramatic method, we have derived analytical results for diagonal and transverse conductivities and determined nonlinear signals. The analytical and numerical results on BMR and NPHE indicate the possibility of determining the material constants, such as the Fermi wave vector and spin-orbit coupling parameter, by simple magnetotransport measurements.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We have considered theoretically nonlinear transport phenomena known as bilinear magnetoresistance (BMR) and nonlinear planar Hall effect (NPHE) within the effective model describing surface states of a 3D topological insulator. Both phenomena can occur in nonmagnetic materials with strong spin-orbit interaction and reveal a term that depends linearly on the charge current density (external electric field) and in-plane magnetic field. In earlier studies, the physical mechanism of BMR and NPHE was related to scattering on spin-momentum locking inhomogeneities or to the hexagonal warping of Dirac cones. Here, we focus on another mechanism related to scattering on impurities that inherently contain spin-orbit coupling. Using the Green's function formalism and diagramatic method, we have derived analytical results for diagonal and transverse conductivities and determined nonlinear signals. The analytical and numerical results on BMR and NPHE indicate the possibility of determining the material constants, such as the Fermi wave vector and spin-orbit coupling parameter, by simple magnetotransport measurements. Close https://link.aps.org/doi/10.1103/PhysRevB.109.155420 doi:10.1103/PhysRevB.109.155420 Close
57.	Piotr Trocha, Thibaut Jonckheere, Jérôme Rech, Thierry Martin Out-of-equilibrium voltage and thermal bias response of a quantum dot hybrid system coupled to topological superconductor Journal of Magnetism and Magnetic Materials, 596 , pp. 171922, 2024. Abstract \| Links \| BibTeX @article{Trocha2024, title = {Out-of-equilibrium voltage and thermal bias response of a quantum dot hybrid system coupled to topological superconductor}, author = {Piotr Trocha and Thibaut Jonckheere and Jérôme Rech and Thierry Martin}, url = {https://www.sciencedirect.com/science/article/pii/S0304885324002130?via%3Dihub}, doi = {/10.1016/j.jmmm.2024.171922}, year = {2024}, date = {2024-04-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {596}, pages = {171922}, abstract = {We investigate theoretically the out-of-equilibrium transport properties of a single-level quantum dot coupled to a normal metal electrode and attached to a topological superconductor. Both voltage and thermal bias responses of the system in the nonequilibrium regime are studied. To obtain transport characteristics we used the nonequilibrium Green’s function approach. Particularly, we calculated the current and the corresponding differential conductance in two distinct cases. In the former situation, the charge current is induced by applying a bias voltage, whereas in the latter case it is generated by setting a temperature difference between the leads with no bias voltage. Moreover, strong diode effect in thermally generated current is found and non-equilibrium thermopower is analyzed.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We investigate theoretically the out-of-equilibrium transport properties of a single-level quantum dot coupled to a normal metal electrode and attached to a topological superconductor. Both voltage and thermal bias responses of the system in the nonequilibrium regime are studied. To obtain transport characteristics we used the nonequilibrium Green’s function approach. Particularly, we calculated the current and the corresponding differential conductance in two distinct cases. In the former situation, the charge current is induced by applying a bias voltage, whereas in the latter case it is generated by setting a temperature difference between the leads with no bias voltage. Moreover, strong diode effect in thermally generated current is found and non-equilibrium thermopower is analyzed. Close https://www.sciencedirect.com/science/article/pii/S0304885324002130?via%3Dihub doi:/10.1016/j.jmmm.2024.171922 Close
56.	Kacper Wrześniewski, Ireneusz Weymann Cross-correlations between currents and tunnel magnetoresistance in interacting double quantum dot-Majorana wire system Scientific Reports, 14 (7815), 2024. Abstract \| Links \| BibTeX @article{Wrześniewski2024, title = {Cross-correlations between currents and tunnel magnetoresistance in interacting double quantum dot-Majorana wire system}, author = {Kacper Wrześniewski and Ireneusz Weymann }, url = {https://link.springer.com/article/10.1038/s41598-024-58344-9}, doi = {10.1038/s41598-024-58344-9}, year = {2024}, date = {2024-04-03}, journal = {Scientific Reports}, volume = {14}, number = {7815}, abstract = {We theoretically investigate the spin and charge transport properties of a double quantum dot coupled to distinct edges of the nanowire hosting Majorana zero-energy modes. The focus is on the analysis of the currents flowing through the left and right junctions and their cross-correlations. We show that the system reveals very different transport properties depending on the detuning protocol of the quantum dot energy levels. For the symmetric detuning, the current dependencies reveal only two maxima associated with resonant tunneling, and currents in the left and right arms of the system reveal weak positive cross-correlations. On the other hand, for antisymmetric detuning, the flow of electrons into drains is maximized and strongly correlated in one bias voltage direction, while for the opposite bias direction a spin blockade is predicted. Furthermore, we observe a suppression of the current cross-correlations at a highly symmetric detuning point, indicating the involvement of the Majorana zero-energy modes in the transport processes. To gain insight into the role of the spin polarization of the Majorana edge states, we analyze the spin-dependent transport characteristics by considering the relationship between the spin canting angle, which describes the coupling of the Majorana modes to the spin of the quantum dots, and the magnetic configurations of the ferromagnetic drains. Moreover, we examine the non-local zero bias anomaly in the differential conductance, detailed analysis of which revealed a specific operational mode of the device that can facilitate the identification of the Majorana presence in the quantum dot-Majorana wire system. Finally, we also consider the transport properties in different magnetic configurations of the system and discuss the behavior of the associated tunnel magnetoresistance.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We theoretically investigate the spin and charge transport properties of a double quantum dot coupled to distinct edges of the nanowire hosting Majorana zero-energy modes. The focus is on the analysis of the currents flowing through the left and right junctions and their cross-correlations. We show that the system reveals very different transport properties depending on the detuning protocol of the quantum dot energy levels. For the symmetric detuning, the current dependencies reveal only two maxima associated with resonant tunneling, and currents in the left and right arms of the system reveal weak positive cross-correlations. On the other hand, for antisymmetric detuning, the flow of electrons into drains is maximized and strongly correlated in one bias voltage direction, while for the opposite bias direction a spin blockade is predicted. Furthermore, we observe a suppression of the current cross-correlations at a highly symmetric detuning point, indicating the involvement of the Majorana zero-energy modes in the transport processes. To gain insight into the role of the spin polarization of the Majorana edge states, we analyze the spin-dependent transport characteristics by considering the relationship between the spin canting angle, which describes the coupling of the Majorana modes to the spin of the quantum dots, and the magnetic configurations of the ferromagnetic drains. Moreover, we examine the non-local zero bias anomaly in the differential conductance, detailed analysis of which revealed a specific operational mode of the device that can facilitate the identification of the Majorana presence in the quantum dot-Majorana wire system. Finally, we also consider the transport properties in different magnetic configurations of the system and discuss the behavior of the associated tunnel magnetoresistance. Close https://link.springer.com/article/10.1038/s41598-024-58344-9 doi:10.1038/s41598-024-58344-9 Close
55.	Amir N. Zarezad, Józef Barnaś, Alireza Qaiumzadeh, Anna Dyrdał Bilinear Planar Hall Effect in Topological Insulators Due to Spin-Momentum Locking Inhomogeneity physica status solidi (RRL) – Rapid Research Letters, 18 (3), pp. 2200483, 2024. Abstract \| Links \| BibTeX @article{Zarezad2024c, title = {Bilinear Planar Hall Effect in Topological Insulators Due to Spin-Momentum Locking Inhomogeneity}, author = {Amir N. Zarezad and Józef Barnaś and Alireza Qaiumzadeh and Anna Dyrdał}, url = {https://doi.org/10.1002/pssr.202200483}, doi = {10.1002/pssr.202200483}, year = {2024}, date = {2024-03-13}, journal = {physica status solidi (RRL) – Rapid Research Letters}, volume = {18}, number = {3}, pages = {2200483}, abstract = {Herein, the effect of spin-momentum locking inhomogeneity on the planar Hall effect in topological insulators (TIs) is studied. Using the minimal model describing surface states of 3D TIs and semiclassical Boltzmann formalism, the planar Hall conductivity (PHC) within the generalized relaxation time approximation is derived. Herein, it is found that the total PHC consists of linear and nonlinear (in electric field) components. The linear term is a conventional PHC which scales quadratically with an external magnetic field, whereas the nonlinear term reveals bilinear behavior, that is, changes its sign when either charge current density or in-plane magnetic-field orientation is reversed. It is shown that the emergent nonlinear planar Hall effect is a consequence of spin-momentum locking inhomogeneity in the TIs with isotropic energy dispersion, and dominates over the conventional planar Hall effect.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Herein, the effect of spin-momentum locking inhomogeneity on the planar Hall effect in topological insulators (TIs) is studied. Using the minimal model describing surface states of 3D TIs and semiclassical Boltzmann formalism, the planar Hall conductivity (PHC) within the generalized relaxation time approximation is derived. Herein, it is found that the total PHC consists of linear and nonlinear (in electric field) components. The linear term is a conventional PHC which scales quadratically with an external magnetic field, whereas the nonlinear term reveals bilinear behavior, that is, changes its sign when either charge current density or in-plane magnetic-field orientation is reversed. It is shown that the emergent nonlinear planar Hall effect is a consequence of spin-momentum locking inhomogeneity in the TIs with isotropic energy dispersion, and dominates over the conventional planar Hall effect. Close https://doi.org/10.1002/pssr.202200483 doi:10.1002/pssr.202200483 Close
54.	Anand Manaparambil, Ireneusz Weymann Spin-resolved nonequilibrium thermopower of asymmetric nanojunctions Phys. Rev. B, 109 , pp. 115402, 2024. Abstract \| Links \| BibTeX @article{Manaparambil2024b, title = {Spin-resolved nonequilibrium thermopower of asymmetric nanojunctions}, author = {Anand Manaparambil and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.115402}, doi = {10.1103/PhysRevB.109.115402}, year = {2024}, date = {2024-03-04}, journal = {Phys. Rev. B}, volume = {109}, pages = { 115402}, abstract = {The spin-resolved thermoelectric transport properties of correlated nanoscale junctions, consisting of a quantum dot/molecule asymmetrically coupled to external ferromagnetic contacts, are studied theoretically in the far-from-equilibrium regime. One of the leads is assumed to be strongly coupled to the quantum dot resulting in the development of the Kondo effect. The spin-dependent current flowing through the system, as well as the thermoelectric properties, are calculated by performing a perturbation expansion with respect to the weakly coupled electrode, while the Kondo correlations are captured accurately by using the numerical renormalization group method. In particular, we determine the differential and nonequilibrium Seebeck effects of the considered system in different magnetic configurations and uncover the crucial role of spin-dependent tunneling on the device performance. Moreover, by allowing for the spin accumulation in the leads, which gives rise to finite spin bias, we shed light on the behavior of the nonequilibrium spin Seebeck effect. In particular, we predict new sign changes of the spin-resolved Seebeck effect in the nonlinear response regime, which stem from the interplay of exchange field and finite voltage and temperature gradients.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close The spin-resolved thermoelectric transport properties of correlated nanoscale junctions, consisting of a quantum dot/molecule asymmetrically coupled to external ferromagnetic contacts, are studied theoretically in the far-from-equilibrium regime. One of the leads is assumed to be strongly coupled to the quantum dot resulting in the development of the Kondo effect. The spin-dependent current flowing through the system, as well as the thermoelectric properties, are calculated by performing a perturbation expansion with respect to the weakly coupled electrode, while the Kondo correlations are captured accurately by using the numerical renormalization group method. In particular, we determine the differential and nonequilibrium Seebeck effects of the considered system in different magnetic configurations and uncover the crucial role of spin-dependent tunneling on the device performance. Moreover, by allowing for the spin accumulation in the leads, which gives rise to finite spin bias, we shed light on the behavior of the nonequilibrium spin Seebeck effect. In particular, we predict new sign changes of the spin-resolved Seebeck effect in the nonlinear response regime, which stem from the interplay of exchange field and finite voltage and temperature gradients. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.115402 doi:10.1103/PhysRevB.109.115402 Close
53.	Piotr Pigoń, Anna Dyrdał Electronic and topological properties of a topological insulator sandwiched between ferromagnetic insulators Journal of Magnetism and Magnetic Materials, 593 , pp. 171795, 2024. Abstract \| Links \| BibTeX @article{Pigon2024, title = {Electronic and topological properties of a topological insulator sandwiched between ferromagnetic insulators}, author = {Piotr Pigoń and Anna Dyrdał }, url = {https://doi.org/10.1016/j.jmmm.2024.171795}, doi = {10.1016/j.jmmm.2024.171795}, year = {2024}, date = {2024-03-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {593}, pages = {171795}, abstract = {We consider a film of a topological insulator (TI) sandwiched between two ferromagnetic (FM) layers. The system is additionally under an external gate voltage. The surface electron states of TI are magnetized due to the magnetic proximity effect to the ferromagnetic layers. The magnetization of ferromagnetic layers can be changed by applying an external magnetic field or by varying thickness of the topological insulator (owing to the interlayer exchange coupling). The change in the magnetic configuration of the system affects the transport properties of the surface electronic states. Using the Green function formalism, we calculate spin polarization, anomalous Hall effect, and magnetoresistance of the system. We show, among others, that by tuning the gate voltage and magnetizations of the top and bottom FM layers, one can observe the topological transition to the quantum anomalous Hall state.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We consider a film of a topological insulator (TI) sandwiched between two ferromagnetic (FM) layers. The system is additionally under an external gate voltage. The surface electron states of TI are magnetized due to the magnetic proximity effect to the ferromagnetic layers. The magnetization of ferromagnetic layers can be changed by applying an external magnetic field or by varying thickness of the topological insulator (owing to the interlayer exchange coupling). The change in the magnetic configuration of the system affects the transport properties of the surface electronic states. Using the Green function formalism, we calculate spin polarization, anomalous Hall effect, and magnetoresistance of the system. We show, among others, that by tuning the gate voltage and magnetizations of the top and bottom FM layers, one can observe the topological transition to the quantum anomalous Hall state. Close https://doi.org/10.1016/j.jmmm.2024.171795 doi:10.1016/j.jmmm.2024.171795 Close
52.	Vrishali Sonar, Piotr Trocha Non-local thermoelectric transport in multi-terminal quantum dot hybrid system Journal of Magnetism and Magnetic Materials, 593 , pp. 171745, 2024. Abstract \| Links \| BibTeX @article{Sonar2024, title = {Non-local thermoelectric transport in multi-terminal quantum dot hybrid system}, author = {Vrishali Sonar and Piotr Trocha}, url = {https://www.sciencedirect.com/science/article/pii/S0304885324000350?via%3Dihub}, doi = {10.1016/j.jmmm.2024.171745}, year = {2024}, date = {2024-03-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {593}, pages = {171745}, abstract = {The heat and charge transport is studied in a hybrid multi-terminal device consisting of one metallic, one ferromagnetic and a superconducting lead coupled to quantum dot. The basic thermoelectric properties of the system are examined using non-equilibrium Green’s function method with finite on-dot Coulomb repulsion within Hubbard-I approximation. Local and non-local transport coefficients including electrical and thermal conductance, Seebeck coefficient calculated in the linear response regime. Main objective is to analyze effect of superconductor coupling and ferromagnet’s spin polarization on thermoelectric transport and how ferromagnetic lead modifies it. We also studied the role of different electron tunneling types, i. e. Andreev reflection, quasi-particle and normal single particle tunneling processes on thermoelectric properties of the considered system.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close The heat and charge transport is studied in a hybrid multi-terminal device consisting of one metallic, one ferromagnetic and a superconducting lead coupled to quantum dot. The basic thermoelectric properties of the system are examined using non-equilibrium Green’s function method with finite on-dot Coulomb repulsion within Hubbard-I approximation. Local and non-local transport coefficients including electrical and thermal conductance, Seebeck coefficient calculated in the linear response regime. Main objective is to analyze effect of superconductor coupling and ferromagnet’s spin polarization on thermoelectric transport and how ferromagnetic lead modifies it. We also studied the role of different electron tunneling types, i. e. Andreev reflection, quasi-particle and normal single particle tunneling processes on thermoelectric properties of the considered system. Close https://www.sciencedirect.com/science/article/pii/S0304885324000350?via%3Dihub doi:10.1016/j.jmmm.2024.171745 Close
51.	Krzysztof P. Wójcik, Tadeusz Domański, Ireneusz Weymann Signatures of Kondo-Majorana interplay in ac response Phys. Rev. B, 109 , pp. 075432, 2024. Abstract \| Links \| BibTeX @article{Wójcik2024, title = {Signatures of Kondo-Majorana interplay in ac response}, author = {Krzysztof P. Wójcik and Tadeusz Domański and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.075432}, doi = {10.1103/PhysRevB.109.075432}, year = {2024}, date = {2024-02-26}, journal = {Phys. Rev. B}, volume = {109}, pages = {075432}, abstract = {We analyze dynamical transport properties of a hybrid nanostructure, comprising a correlated quantum dot embedded between the source and drain electrodes, which are subject to an ac voltage, focusing on signatures imprinted on the charge transport by the side-attached Majorana zero-energy mode. The considerations are based on the Kubo formula, for which the relevant correlation functions are determined by using the numerical renormalization group approach, which allows us to consider the correlation effects due to the Coulomb repulsion and their interplay with the Majorana mode in a nonperturbative manner. We point out universal features of the dynamical conductance, showing up in the Kondo-Majorana regime, and differentiate them against the conventional Kondo and Majorana systems. In particular, we predict that the Majorana quasiparticles give rise to universal fractional values of the ac conductance in the well-defined frequency range below the peak at the Kondo scale. We also show this Kondo scale to actually increase with strengthening the coupling to the topological superconducting wire.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We analyze dynamical transport properties of a hybrid nanostructure, comprising a correlated quantum dot embedded between the source and drain electrodes, which are subject to an ac voltage, focusing on signatures imprinted on the charge transport by the side-attached Majorana zero-energy mode. The considerations are based on the Kubo formula, for which the relevant correlation functions are determined by using the numerical renormalization group approach, which allows us to consider the correlation effects due to the Coulomb repulsion and their interplay with the Majorana mode in a nonperturbative manner. We point out universal features of the dynamical conductance, showing up in the Kondo-Majorana regime, and differentiate them against the conventional Kondo and Majorana systems. In particular, we predict that the Majorana quasiparticles give rise to universal fractional values of the ac conductance in the well-defined frequency range below the peak at the Kondo scale. We also show this Kondo scale to actually increase with strengthening the coupling to the topological superconducting wire. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.075432 doi:10.1103/PhysRevB.109.075432 Close
50.	Wojciech Rudziński, Józef Barnaś, Anna Dyrdał Spin waves in bilayers of transition metal dichalcogenides Physical Review B, 109 , pp. 035412, 2024. Abstract \| Links \| BibTeX @article{Rudziński2024, title = {Spin waves in bilayers of transition metal dichalcogenides}, author = {Wojciech Rudziński and Józef Barnaś and Anna Dyrdał}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.035412}, doi = {10.1103/PhysRevB.109.035412}, year = {2024}, date = {2024-01-11}, journal = {Physical Review B}, volume = {109}, pages = {035412}, abstract = {Van der Waals magnetic materials are currently of great interest as materials for applications in future ultrathin nanoelectronics and nanospintronics. Due to weak coupling between individual monolayers, these materials can be easily obtained in the monolayer and bilayer forms. The latter are of specific interest as they may be considered as natural two-dimensional spin valves. In this paper, we theoretically study spin waves in bilayers of transition metal dichalcogenides. The considerations are carried within the general spin wave theory based on effective spin Hamiltonian and Holstein-Primakoff-Bogolubov transformation. The spin Hamiltonian includes intralayer as well as interlayer nearest-neighbor exchange interactions, easy-plane anisotropy, and additionally a weak in-plane easy-axis anisotropy. The bilayer systems consist of two ferromagnetic (in-plane magnetization) monolayers that are coupled either ferromagnetically or antiferromagnetically. In the latter case, we analyze the spin-wave spectra in all magnetic phases, i.e., in the antiferromagnetic, spin-flop, and ferromagnetic ones.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Van der Waals magnetic materials are currently of great interest as materials for applications in future ultrathin nanoelectronics and nanospintronics. Due to weak coupling between individual monolayers, these materials can be easily obtained in the monolayer and bilayer forms. The latter are of specific interest as they may be considered as natural two-dimensional spin valves. In this paper, we theoretically study spin waves in bilayers of transition metal dichalcogenides. The considerations are carried within the general spin wave theory based on effective spin Hamiltonian and Holstein-Primakoff-Bogolubov transformation. The spin Hamiltonian includes intralayer as well as interlayer nearest-neighbor exchange interactions, easy-plane anisotropy, and additionally a weak in-plane easy-axis anisotropy. The bilayer systems consist of two ferromagnetic (in-plane magnetization) monolayers that are coupled either ferromagnetically or antiferromagnetically. In the latter case, we analyze the spin-wave spectra in all magnetic phases, i.e., in the antiferromagnetic, spin-flop, and ferromagnetic ones. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.035412 doi:10.1103/PhysRevB.109.035412 Close
49.	Amir N. Zarezad, Józef Barnaś, Anna Dyrdał, Alireza Qaiumzadeh Skyrmion-deriven topological spin and charge Hall effects in diffusive antiferromagnetic thin films Journal of Magnetism and Magnetic Materials, 589 , pp. 171599, 2024. Abstract \| Links \| BibTeX @article{Zarezad2024, title = {Skyrmion-deriven topological spin and charge Hall effects in diffusive antiferromagnetic thin films}, author = {Amir N. Zarezad and Józef Barnaś and Anna Dyrdał and Alireza Qaiumzadeh}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323012490?via%3Dihub}, doi = {10.1016/j.jmmm.2023.171599}, year = {2024}, date = {2024-01-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {589}, pages = { 171599}, abstract = {We investigate topological Hall effects in a metallic antiferromagnetic (AFM) thin film and/or at the interface of an AFM insulator–normal metal bilayer with a single skyrmion in the diffusive regime. To determine the spin- and charge Hall currents, we employed a Boltzmann kinetic equation with both spin-dependent and spin-flip scatterings. The interaction between conduction electrons and static skyrmions is included in the Boltzmann equation via the corresponding emergent magnetic field arising from the skyrmion texture. We compute intrinsic and extrinsic contributions to the topological spin Hall effect and spin accumulation, induced by an AFM skyrmion. We show that although the spin Hall current vanishes rapidly outside the skyrmion, the spin accumulation can be finite at the edges far from the skyrmion, provided the spin diffusion length is longer than the skyrmion radius. In addition, We show that in the presence of a spin-dependent relaxation time, the topological charge Hall effect is finite and we determine the corresponding Hall voltage. Our results may help to explore antiferromagnetic skyrmions by electrical means in real materials.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We investigate topological Hall effects in a metallic antiferromagnetic (AFM) thin film and/or at the interface of an AFM insulator–normal metal bilayer with a single skyrmion in the diffusive regime. To determine the spin- and charge Hall currents, we employed a Boltzmann kinetic equation with both spin-dependent and spin-flip scatterings. The interaction between conduction electrons and static skyrmions is included in the Boltzmann equation via the corresponding emergent magnetic field arising from the skyrmion texture. We compute intrinsic and extrinsic contributions to the topological spin Hall effect and spin accumulation, induced by an AFM skyrmion. We show that although the spin Hall current vanishes rapidly outside the skyrmion, the spin accumulation can be finite at the edges far from the skyrmion, provided the spin diffusion length is longer than the skyrmion radius. In addition, We show that in the presence of a spin-dependent relaxation time, the topological charge Hall effect is finite and we determine the corresponding Hall voltage. Our results may help to explore antiferromagnetic skyrmions by electrical means in real materials. Close https://www.sciencedirect.com/science/article/pii/S0304885323012490?via%3Dihub doi:10.1016/j.jmmm.2023.171599 Close
48.	Anna Krzyżewska, Anna Dyrdał Bilinear magnetoresistance in 2DEG with isotropic cubic Rashba spin–orbit interaction Journal of Magnetism and Magnetic Materials, 589 , pp. 171615, 2024. Abstract \| Links \| BibTeX @article{Krzyżewska2024, title = {Bilinear magnetoresistance in 2DEG with isotropic cubic Rashba spin–orbit interaction}, author = {Anna Krzyżewska and Anna Dyrdał}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323012659?via%3Dihub}, doi = {10.1016/j.jmmm.2023.171615}, year = {2024}, date = {2024-01-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {589}, pages = {171615}, abstract = {Bilinear magnetoresistance has been studied theoretically in 2D systems with isotropic cubic form of Rashba spin–orbit interaction. We have derived the effective spin–orbital field due to current-induced spin polarization and discussed its contribution to the unidirectional system response. The analyzed model can be applied to the semiconductor quantum wells as well as 2DEG at the surfaces and interfaces of perovskite oxides.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Bilinear magnetoresistance has been studied theoretically in 2D systems with isotropic cubic form of Rashba spin–orbit interaction. We have derived the effective spin–orbital field due to current-induced spin polarization and discussed its contribution to the unidirectional system response. The analyzed model can be applied to the semiconductor quantum wells as well as 2DEG at the surfaces and interfaces of perovskite oxides. Close https://www.sciencedirect.com/science/article/pii/S0304885323012659?via%3Dihub doi:10.1016/j.jmmm.2023.171615 Close
47.	Mirali Jafari, Anna Dyrdał Effect of strain on the electronic and magnetic properties of bilayer T-phase VS2 : A first-principles study Journal of Magnetism and Magnetic Materials, 589 , pp. 171618, 2024. Abstract \| Links \| BibTeX @article{Jafari2024, title = {Effect of strain on the electronic and magnetic properties of bilayer T-phase VS2 : A first-principles study}, author = {Mirali Jafari and Anna Dyrdał}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323012684?via%3Dihub}, doi = {10.1016/j.jmmm.2023.171618}, year = {2024}, date = {2024-01-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {589}, pages = {171618}, abstract = {Using the Density Functional Theory (DFT) calculations, we determined the electronic and magnetic properties of a T-phase VS2 bilayer as a function of tensile and compressive strain. First, we determine the ground state structural parameters and then the band structure, magnetic anisotropy, exchange parameters, and Curie temperature. Variation of these parameters with the strain is carefully analyzed and described. The easy-plane anisotropy, which is rather small in the absence of strain, becomes remarkably enhanced by tensile strain and reduced almost to zero by compressive strain. We also show that the exchange parameters and the Curie temperature are remarkably reduced for the compressive strains below roughly −4%. }, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Using the Density Functional Theory (DFT) calculations, we determined the electronic and magnetic properties of a T-phase VS2 bilayer as a function of tensile and compressive strain. First, we determine the ground state structural parameters and then the band structure, magnetic anisotropy, exchange parameters, and Curie temperature. Variation of these parameters with the strain is carefully analyzed and described. The easy-plane anisotropy, which is rather small in the absence of strain, becomes remarkably enhanced by tensile strain and reduced almost to zero by compressive strain. We also show that the exchange parameters and the Curie temperature are remarkably reduced for the compressive strains below roughly −4%. Close https://www.sciencedirect.com/science/article/pii/S0304885323012684?via%3Dihub doi:10.1016/j.jmmm.2023.171618 Close
46.	Emil Siuda, Piotr Trocha Thermal generation of spin current in a quantum dot coupled to magnetic insulators Journal of Magnetism and Magnetic Materials, 589 , pp. 171495, 2024. Abstract \| Links \| BibTeX @article{Siuda2024, title = {Thermal generation of spin current in a quantum dot coupled to magnetic insulators}, author = {Emil Siuda and Piotr Trocha}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323011459}, doi = {/10.1016/j.jmmm.2023.171495}, year = {2024}, date = {2024-01-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {589}, pages = {171495}, abstract = {In this work, we study thermally-generated spin current in the system consisting of a quantum dot connected to two magnetic insulators. The external leads are kept at different temperatures which leads to an imbalance of magnon populations in two magnetic insulators resulting in the flow of the magnon (spin) current. We take into account many-body magnon interactions and incorporate energy-dependent density of states of the magnetic insulators. Both features can strongly affect magnon distribution in the magnetic insulators and the coupling strengths between the leads and the dot, and thus, the thermally generated spin current. All the calculations are carried out in the weak coupling regime. We show, that results obtained with a density of states being a function of energy differ significantly from the ones obtained with a density of states taken as a constant. In turn, magnon interactions in the leads proved to be important at high temperatures and large values of energy of transported spin waves.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close In this work, we study thermally-generated spin current in the system consisting of a quantum dot connected to two magnetic insulators. The external leads are kept at different temperatures which leads to an imbalance of magnon populations in two magnetic insulators resulting in the flow of the magnon (spin) current. We take into account many-body magnon interactions and incorporate energy-dependent density of states of the magnetic insulators. Both features can strongly affect magnon distribution in the magnetic insulators and the coupling strengths between the leads and the dot, and thus, the thermally generated spin current. All the calculations are carried out in the weak coupling regime. We show, that results obtained with a density of states being a function of energy differ significantly from the ones obtained with a density of states taken as a constant. In turn, magnon interactions in the leads proved to be important at high temperatures and large values of energy of transported spin waves. Close https://www.sciencedirect.com/science/article/pii/S0304885323011459 doi:/10.1016/j.jmmm.2023.171495 Close
2023
45.	Wojciech Rudziński, Józef Barnaś, Anna Dyrdał Spin waves in monolayers of transition-metal dichalcogenides with Dzyaloshinskii - Moriya interaction Journal of Magnetism and Magnetic Materials, 588 , pp. 171463, 2023. Abstract \| Links \| BibTeX @article{Rudzinski2023, title = {Spin waves in monolayers of transition-metal dichalcogenides with Dzyaloshinskii - Moriya interaction}, author = {Wojciech Rudziński and Józef Barnaś and Anna Dyrdał}, url = {https://doi.org/10.1016/j.jmmm.2023.171463}, doi = {10.1016/j.jmmm.2023.171463}, year = {2023}, date = {2023-12-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {588}, pages = {171463}, abstract = {Dzyaloshinski–Moriya interaction, known also as the antisymmetric exchange coupling, leads to a variety of interesting spin phenomena, like spin canting, skyrmion formation, nonreciprocal spin wave propagation, and others. In this paper we analyze spin waves in monolayers of two-dimensional van–der–Waals materials, such as Vanadium–based dichalcogenides, VX2 (X=S, Se, Te) and other materials of similar symmetry. The considerations are limited to a collinear spin ground state, stabilized by a sufficiently strong magnetic anisotropy. The theoretical analysis is performed within the general spin wave theory based on the Holstein–Primakoff–Bogoliubov transformation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Dzyaloshinski–Moriya interaction, known also as the antisymmetric exchange coupling, leads to a variety of interesting spin phenomena, like spin canting, skyrmion formation, nonreciprocal spin wave propagation, and others. In this paper we analyze spin waves in monolayers of two-dimensional van–der–Waals materials, such as Vanadium–based dichalcogenides, VX2 (X=S, Se, Te) and other materials of similar symmetry. The considerations are limited to a collinear spin ground state, stabilized by a sufficiently strong magnetic anisotropy. The theoretical analysis is performed within the general spin wave theory based on the Holstein–Primakoff–Bogoliubov transformation. Close https://doi.org/10.1016/j.jmmm.2023.171463 doi:10.1016/j.jmmm.2023.171463 Close
44.	Anand Manaparambil, Ireneusz Weymann Giant tunnel magnetoresistance induced by thermal bias Journal of Magnetism and Magnetic Materials, 587 , pp. 171272, 2023. Abstract \| Links \| BibTeX @article{Manaparambil2023b, title = {Giant tunnel magnetoresistance induced by thermal bias}, author = {Anand Manaparambil and Ireneusz Weymann}, url = {https://www.sciencedirect.com/science/article/pii/S0304885323009228}, doi = {10.1016/j.jmmm.2023.171272}, year = {2023}, date = {2023-12-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {587}, pages = {171272}, abstract = {We analyze the spin-resolved transport and, in particular, the tunnel magnetoresistance of an asymmetric ferromagnetic tunnel junction with an embedded quantum dot or molecule subject to thermal and voltage bias in the nonlinear response regime. We demonstrate that such system exhibits a giant tunnel magnetoresistance effect that can be tuned by gate and bias voltages. Large values of magnetoresistance are associated with the interplay between the Kondo correlations and the ferromagnetic-contact-induced exchange field. In particular, we show that the nonequilibrium current in the parallel and antiparallel magnetic configuration of the system changes sign at different values of the voltage and thermal bias. This gives rise to giant values of magnetoresistance, the sign of which can be controlled by the applied sources.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We analyze the spin-resolved transport and, in particular, the tunnel magnetoresistance of an asymmetric ferromagnetic tunnel junction with an embedded quantum dot or molecule subject to thermal and voltage bias in the nonlinear response regime. We demonstrate that such system exhibits a giant tunnel magnetoresistance effect that can be tuned by gate and bias voltages. Large values of magnetoresistance are associated with the interplay between the Kondo correlations and the ferromagnetic-contact-induced exchange field. In particular, we show that the nonequilibrium current in the parallel and antiparallel magnetic configuration of the system changes sign at different values of the voltage and thermal bias. This gives rise to giant values of magnetoresistance, the sign of which can be controlled by the applied sources. Close https://www.sciencedirect.com/science/article/pii/S0304885323009228 doi:10.1016/j.jmmm.2023.171272 Close
43.	Mirali Jafari, Wojciech Rudziński, Józef Barnaś, Anna Dyrdał Electronic and magnetic properties of 2D vanadium-based transition metal dichalcogenides Scientific Reports, 13 , pp. 20947, 2023. Abstract \| Links \| BibTeX @article{Jafari2023, title = {Electronic and magnetic properties of 2D vanadium-based transition metal dichalcogenides}, author = {Mirali Jafari and Wojciech Rudziński and Józef Barnaś and Anna Dyrdał}, url = {https://doi.org/10.1038/s41598-023-48141-1}, doi = {10.1038/s41598-023-48141-1}, year = {2023}, date = {2023-11-28}, journal = {Scientific Reports}, volume = {13}, pages = {20947}, abstract = {In this paper, electronic and magnetic properties of monolayers and bilayers of Vanadium-based transition metal dichalcogenides VX2 (X = S, Se, Te) in the H phase are investigated theoretically using methods based on DFT calculations as well as analytical methods based on effective spin Hamiltonians. The band structure has been computed for all systems, and then the results have been used to determine exchange parameters and magnetic anisotropy constants. These parameters are subsequently used for the determination of the Curie temperatures, hysteresis curves, and energy of spin-wave excitations. In the latter case, we compare analytical results based on effective spin Hamiltonian with those determined numerically by Quantum ATK software and find a good agreement. The determined Curie temperature for VTe2 monolayers and bilayers is below the room temperature (especially that for bilayers), while for the other two materials, i.e. for VS2 and VSe2, it is above the room temperature, in agreement with available experimental data.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close In this paper, electronic and magnetic properties of monolayers and bilayers of Vanadium-based transition metal dichalcogenides VX2 (X = S, Se, Te) in the H phase are investigated theoretically using methods based on DFT calculations as well as analytical methods based on effective spin Hamiltonians. The band structure has been computed for all systems, and then the results have been used to determine exchange parameters and magnetic anisotropy constants. These parameters are subsequently used for the determination of the Curie temperatures, hysteresis curves, and energy of spin-wave excitations. In the latter case, we compare analytical results based on effective spin Hamiltonian with those determined numerically by Quantum ATK software and find a good agreement. The determined Curie temperature for VTe2 monolayers and bilayers is below the room temperature (especially that for bilayers), while for the other two materials, i.e. for VS2 and VSe2, it is above the room temperature, in agreement with available experimental data. Close https://doi.org/10.1038/s41598-023-48141-1 doi:10.1038/s41598-023-48141-1 Close
42.	Kacper Wrześniewski, Tomasz Ślusarski, Ireneusz Weymann Nonmonotonic buildup of spin-singlet correlations in a double quantum dot Physical Review B, 108 , pp. 144307, 2023. Abstract \| Links \| BibTeX @article{Wrześniewski2023b, title = {Nonmonotonic buildup of spin-singlet correlations in a double quantum dot}, author = {Kacper Wrześniewski and Tomasz Ślusarski and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.108.144307}, doi = {10.1103/PhysRevB.108.144307}, year = {2023}, date = {2023-10-27}, journal = {Physical Review B}, volume = {108}, pages = {144307}, abstract = {Dynamical buildup of spin-singlet correlations between the two quantum dots is investigated by means of the time-dependent numerical renormalization group method. By calculating the time evolution of the spin-spin expectation value upon a quench in the hopping between the quantum dots, we examine the timescales associated with the development of an entangled spin-singlet state in the system. Interestingly, we predict a nonmonotonic buildup of entanglement between the two dots. In particular, we find that in short timescales the effective exchange interaction between the quantum dots is of ferromagnetic type, favoring spin-triplet correlations, as opposed to the long-time limit, when strong antiferromagnetic correlations develop and eventually an entangled spin-singlet state is formed between the dots. We also numerically determine the relevant timescales and show that the physics is generally governed by the interplay between the Kondo correlations on each dot and exchange interaction between the spins of both quantum dots.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Dynamical buildup of spin-singlet correlations between the two quantum dots is investigated by means of the time-dependent numerical renormalization group method. By calculating the time evolution of the spin-spin expectation value upon a quench in the hopping between the quantum dots, we examine the timescales associated with the development of an entangled spin-singlet state in the system. Interestingly, we predict a nonmonotonic buildup of entanglement between the two dots. In particular, we find that in short timescales the effective exchange interaction between the quantum dots is of ferromagnetic type, favoring spin-triplet correlations, as opposed to the long-time limit, when strong antiferromagnetic correlations develop and eventually an entangled spin-singlet state is formed between the dots. We also numerically determine the relevant timescales and show that the physics is generally governed by the interplay between the Kondo correlations on each dot and exchange interaction between the spins of both quantum dots. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.108.144307 doi:10.1103/PhysRevB.108.144307 Close
41.	Alexandre Huguet, Kacper Wrześniewski, Ireneusz Weymann Spin effects on transport and zero-bias anomaly in a hybrid Majorana wire-quantum dot system Scientific Reports, 13 , pp. 17279, 2023, ISSN: 2045-2322. Abstract \| Links \| BibTeX @article{Huguet2023, title = {Spin effects on transport and zero-bias anomaly in a hybrid Majorana wire-quantum dot system}, author = {Alexandre Huguet and Kacper Wrześniewski and Ireneusz Weymann }, url = {https://www.nature.com/articles/s41598-023-44254-9}, doi = {10.1038/s41598-023-44254-9}, issn = {2045-2322}, year = {2023}, date = {2023-10-12}, journal = {Scientific Reports}, volume = {13}, pages = {17279}, abstract = {We examine the impact of spin effects on the nonequilibrium transport properties of a nanowire hosting Majorana zero-energy modes at its ends, coupled to a quantum dot junction with ferromagnetic leads. Using the real-time diagrammatic technique, we determine the current, differential conductance and current cross-correlations in the nonlinear response regime. We also explore transport in different magnetic configurations of the system, which can be quantified by the tunnel magnetoresistance. We show that the presence of Majorana quasiparticles gives rise to unique features in all spin-resolved transport characteristics, in particular, to zero-bias anomaly, negative differential conductance, negative tunnel magnetoresistance, and it is also reflected in the current cross-correlations. Moreover, we study the dependence of the zero-bias anomaly on various system parameters and demonstrate its dependence on the magnetic configuration of the system as well as on the degree of spin polarization in the leads. A highly nontrivial behavior is also found for the tunnel magnetoresistance, which exhibits regions of enhanced or negative values—new features resulting from the coupling to Majorana wire.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We examine the impact of spin effects on the nonequilibrium transport properties of a nanowire hosting Majorana zero-energy modes at its ends, coupled to a quantum dot junction with ferromagnetic leads. Using the real-time diagrammatic technique, we determine the current, differential conductance and current cross-correlations in the nonlinear response regime. We also explore transport in different magnetic configurations of the system, which can be quantified by the tunnel magnetoresistance. We show that the presence of Majorana quasiparticles gives rise to unique features in all spin-resolved transport characteristics, in particular, to zero-bias anomaly, negative differential conductance, negative tunnel magnetoresistance, and it is also reflected in the current cross-correlations. Moreover, we study the dependence of the zero-bias anomaly on various system parameters and demonstrate its dependence on the magnetic configuration of the system as well as on the degree of spin polarization in the leads. A highly nontrivial behavior is also found for the tunnel magnetoresistance, which exhibits regions of enhanced or negative values—new features resulting from the coupling to Majorana wire. Close https://www.nature.com/articles/s41598-023-44254-9 doi:10.1038/s41598-023-44254-9 Close
40.	Anna Dyrdał, Alireza Qaiumzadeh, Arne Brataas, Józef Barnaś Magnon-plasmon hybridization mediated by spin-orbit interaction in magnetic materials Physical Review B, 108 (4), pp. 045414, 2023. Abstract \| Links \| BibTeX @article{Dyrdał2023, title = {Magnon-plasmon hybridization mediated by spin-orbit interaction in magnetic materials}, author = {Anna Dyrdał and Alireza Qaiumzadeh and Arne Brataas and Józef Barnaś}, url = {https://doi.org/10.1103/PhysRevB.108.045414}, doi = {10.1103/PhysRevB.108.045414}, year = {2023}, date = {2023-07-21}, journal = {Physical Review B}, volume = {108}, number = {4}, pages = {045414}, abstract = {We propose a mechanism for magnon-plasmon coupling and hybridization in ferromagnetic (FM) and antiferromagnetic (AFM) systems. The electric field associated with plasmon oscillations creates a nonequilibrium spin density via the inverse spin galvanic effect. This plasmon-induced spin density couples to magnons by an exchange interaction. The strength of magnon-plasmon coupling depends on the magnetoelectric susceptibility of the system and the wavevector at which the level repulsion has happened. This wavevector may be tuned by an applied magnetic field. In AFM systems, the degeneracy of two chiral magnons is broken in the presence of a magnetic field, and we find two separate hybrid modes for left-handed and right-handed AFM magnons. Furthermore, we show that magnon-plasmon coupling in AFM systems is enhanced because of strong intrasublattice spin dynamics. We argue that the recently discovered two-dimensional magnetic systems are ideal platforms to investigate proposed magnon-plasmon hybrid modes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We propose a mechanism for magnon-plasmon coupling and hybridization in ferromagnetic (FM) and antiferromagnetic (AFM) systems. The electric field associated with plasmon oscillations creates a nonequilibrium spin density via the inverse spin galvanic effect. This plasmon-induced spin density couples to magnons by an exchange interaction. The strength of magnon-plasmon coupling depends on the magnetoelectric susceptibility of the system and the wavevector at which the level repulsion has happened. This wavevector may be tuned by an applied magnetic field. In AFM systems, the degeneracy of two chiral magnons is broken in the presence of a magnetic field, and we find two separate hybrid modes for left-handed and right-handed AFM magnons. Furthermore, we show that magnon-plasmon coupling in AFM systems is enhanced because of strong intrasublattice spin dynamics. We argue that the recently discovered two-dimensional magnetic systems are ideal platforms to investigate proposed magnon-plasmon hybrid modes. Close https://doi.org/10.1103/PhysRevB.108.045414 doi:10.1103/PhysRevB.108.045414 Close
39.	Ali Ebrahimian, Anna Dyrdał, Alireza Qaiumzadeh Control of magnetic states and spin interactions in bilayer CrCl3 with strain and electric fields: an ab initio study Scientific Reports, 13 , pp. 5336, 2023. Abstract \| Links \| BibTeX @article{Ebrahimian2023, title = {Control of magnetic states and spin interactions in bilayer CrCl3 with strain and electric fields: an ab initio study}, author = {Ali Ebrahimian and Anna Dyrdał and Alireza Qaiumzadeh}, url = {https://doi.org/10.1038/s41598-023-32598-1}, doi = {10.1038/s41598-023-32598-1}, year = {2023}, date = {2023-04-01}, journal = {Scientific Reports}, volume = {13}, pages = {5336}, abstract = {Using ab initio density functional theory, we demonstrated the possibility of controlling the magnetic ground-state properties of bilayer CrCl3 by means of mechanical strains and electric fields. In principle, we investigated the influence of these two fields on parameters describing the spin Hamiltonian of the system. The obtained results show that biaxial strains change the magnetic ground state between ferromagnetic and antiferromagnetic phases. The mechanical strain also affects the direction and amplitude of the magnetic anisotropy energy (MAE). Importantly, the direction and amplitude of the Dzyaloshinskii–Moriya vectors are also highly tunable under external strain and electric fields. The competition between nearest-neighbor exchange interactions, MAE, and Dzyaloshinskii–Moriya interactions can lead to the stabilization of various exotic spin textures and novel magnetic excitations. The high tunability of magnetic properties by external fields makes bilayer CrCl3 a promising candidate for application in the emerging field of two-dimensional quantum spintronics and magnonics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Using ab initio density functional theory, we demonstrated the possibility of controlling the magnetic ground-state properties of bilayer CrCl3 by means of mechanical strains and electric fields. In principle, we investigated the influence of these two fields on parameters describing the spin Hamiltonian of the system. The obtained results show that biaxial strains change the magnetic ground state between ferromagnetic and antiferromagnetic phases. The mechanical strain also affects the direction and amplitude of the magnetic anisotropy energy (MAE). Importantly, the direction and amplitude of the Dzyaloshinskii–Moriya vectors are also highly tunable under external strain and electric fields. The competition between nearest-neighbor exchange interactions, MAE, and Dzyaloshinskii–Moriya interactions can lead to the stabilization of various exotic spin textures and novel magnetic excitations. The high tunability of magnetic properties by external fields makes bilayer CrCl3 a promising candidate for application in the emerging field of two-dimensional quantum spintronics and magnonics. Close https://doi.org/10.1038/s41598-023-32598-1 doi:10.1038/s41598-023-32598-1 Close
38.	Kacper Wrześniewski Dynamics of Superconducting Correlations Induced by Hopping in Serial Double Quantum Dot System Acta Physica Polonica A, 143 (2), pp. 160, 2023. Abstract \| Links \| BibTeX @article{Wrześniewski2023, title = {Dynamics of Superconducting Correlations Induced by Hopping in Serial Double Quantum Dot System}, author = {Kacper Wrześniewski}, url = {http://przyrbwn.icm.edu.pl/APP/apphome.html}, doi = {10.12693/APhysPolA.143.160}, year = {2023}, date = {2023-02-27}, journal = {Acta Physica Polonica A}, volume = {143}, number = {2}, pages = {160}, abstract = {We study the quench dynamics of superconducting pairing correlations in the double quantum dotsystem coupled to superconducting and normal metallic electrodes. The quantum dots are initiallyisolated from each other, and the subsequent dynamics are induced by the sudden switching on hoppingbetween them. We focus on the time-dependence of the real and imaginary parts of dots pairing potentialand the role of the hopping amplitude and on-site Coulomb correlations. For relatively small hoppingvalues, the evolution of the pairing potential is suppressed due to a strong single-occupation blockade.As the hopping amplitude increases, the pairing potential is dynamically redistributed between thedots and can eventually assume values of opposite signs. This effect is enhanced by the presence ofstrong on-site Coulomb interactions. The discussed numerical results are obtained by means of thetime-dependent numerical renormalization group approach.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We study the quench dynamics of superconducting pairing correlations in the double quantum dotsystem coupled to superconducting and normal metallic electrodes. The quantum dots are initiallyisolated from each other, and the subsequent dynamics are induced by the sudden switching on hoppingbetween them. We focus on the time-dependence of the real and imaginary parts of dots pairing potentialand the role of the hopping amplitude and on-site Coulomb correlations. For relatively small hoppingvalues, the evolution of the pairing potential is suppressed due to a strong single-occupation blockade.As the hopping amplitude increases, the pairing potential is dynamically redistributed between thedots and can eventually assume values of opposite signs. This effect is enhanced by the presence ofstrong on-site Coulomb interactions. The discussed numerical results are obtained by means of thetime-dependent numerical renormalization group approach. Close http://przyrbwn.icm.edu.pl/APP/apphome.html doi:10.12693/APhysPolA.143.160 Close
37.	Krzysztof Paweł Wójcik, Piotr Majek Majorana Coupling and Kondo Screening of Localized Spins Acta Physica Polonica A, 143 (2), pp. 207, 2023. Abstract \| Links \| BibTeX @article{Wójcik2023, title = {Majorana Coupling and Kondo Screening of Localized Spins}, author = {Krzysztof Paweł Wójcik and Piotr Majek}, url = {http://przyrbwn.icm.edu.pl/APP/PDF/143/app143z2p15.pdf}, doi = {10.12693/APhysPolA.143.207}, year = {2023}, date = {2023-02-27}, journal = {Acta Physica Polonica A}, volume = {143}, number = {2}, pages = {207}, abstract = {We perform a theoretical analysis of the fate of the local magnetic moment of a quantum dot coupled to a normal metallic lead and a topological superconducting wire hosting Majorana modes at the ends. By means of simple analytical tools and numerical renormalization group calculations, we show that the proximity of the Majorana mode reduces the magnetic moment from 1/4, characteristic of a free spin 1/2, to 1/16. Coupling to the normal lead then causes the Kondo effect, such that the magnetic moment is fully screened below the Kondo temperature. The latter is vastly increased for strong coupling to Majorana mode.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We perform a theoretical analysis of the fate of the local magnetic moment of a quantum dot coupled to a normal metallic lead and a topological superconducting wire hosting Majorana modes at the ends. By means of simple analytical tools and numerical renormalization group calculations, we show that the proximity of the Majorana mode reduces the magnetic moment from 1/4, characteristic of a free spin 1/2, to 1/16. Coupling to the normal lead then causes the Kondo effect, such that the magnetic moment is fully screened below the Kondo temperature. The latter is vastly increased for strong coupling to Majorana mode. Close http://przyrbwn.icm.edu.pl/APP/PDF/143/app143z2p15.pdf doi:10.12693/APhysPolA.143.207 Close
36.	Anand Manaparambil, Ireneusz Weymann Nonequilibrium Seebeck effect and thermoelectric efficiency of Kondo-correlated molecular junctions Phys. Rev. B, 107 , pp. 085404, 2023. Abstract \| Links \| BibTeX @article{Manaparambil2023, title = {Nonequilibrium Seebeck effect and thermoelectric efficiency of Kondo-correlated molecular junctions}, author = {Anand Manaparambil and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.107.085404}, doi = {10.1103/PhysRevB.107.085404}, year = {2023}, date = {2023-02-07}, journal = {Phys. Rev. B}, volume = {107}, pages = {085404}, abstract = {We theoretically study the nonequilibrium thermoelectric transport properties of a strongly-correlated molecule (or quantum dot) embedded in a tunnel junction. Assuming that the coupling of the molecule to the contacts is asymmetric, we determine the nonlinear current driven by the voltage and temperature gradients by using the perturbation theory. However, the subsystem consisting of the molecule strongly coupled to one of the contacts is solved by using the numerical renormalization group method, which allows for accurate description of Kondo correlations. We study the temperature gradient and voltage dependence of the nonlinear and differential Seebeck coefficients for various initial configurations of the system. In particular, we show that in the Coulomb blockade regime with singly occupied molecule, both thermopowers exhibit sign changes due to the Kondo correlations at nonequilibrium conditions. Moreover, we determine the nonlinear heat current and thermoelectric efficiency, demonstrating that the system can work as a heat engine with considerable efficiency, depending on the transport regime.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We theoretically study the nonequilibrium thermoelectric transport properties of a strongly-correlated molecule (or quantum dot) embedded in a tunnel junction. Assuming that the coupling of the molecule to the contacts is asymmetric, we determine the nonlinear current driven by the voltage and temperature gradients by using the perturbation theory. However, the subsystem consisting of the molecule strongly coupled to one of the contacts is solved by using the numerical renormalization group method, which allows for accurate description of Kondo correlations. We study the temperature gradient and voltage dependence of the nonlinear and differential Seebeck coefficients for various initial configurations of the system. In particular, we show that in the Coulomb blockade regime with singly occupied molecule, both thermopowers exhibit sign changes due to the Kondo correlations at nonequilibrium conditions. Moreover, we determine the nonlinear heat current and thermoelectric efficiency, demonstrating that the system can work as a heat engine with considerable efficiency, depending on the transport regime. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.107.085404 doi:10.1103/PhysRevB.107.085404 Close
2022
35.	Irina Werner, Jan Griebel, Albert Masip-Sánchez, Xavier López, Karol Załęski, Piotr Kozłowski, Axel Kahnt, Martin Boerner, Ziyan Warneke, Jonas Warneke, Kirill Yu. Monakhov Hybrid Molecular Magnets with Lanthanide- and Countercation-Mediated Interfacial Electron Transfer between Phthalocyanine and Polyoxovanadate Inorganic Chemistry, 62 (9), pp. 3761-3775, 2022, (PMID: 36534941). Links \| BibTeX @article{doi:10.1021/acs.inorgchem.2c03599, title = {Hybrid Molecular Magnets with Lanthanide- and Countercation-Mediated Interfacial Electron Transfer between Phthalocyanine and Polyoxovanadate}, author = {Irina Werner and Jan Griebel and Albert Masip-Sánchez and Xavier López and Karol Załęski and Piotr Kozłowski and Axel Kahnt and Martin Boerner and Ziyan Warneke and Jonas Warneke and Kirill Yu. Monakhov}, url = {https://doi.org/10.1021/acs.inorgchem.2c03599}, doi = {10.1021/acs.inorgchem.2c03599}, year = {2022}, date = {2022-12-19}, journal = {Inorganic Chemistry}, volume = {62}, number = {9}, pages = {3761-3775}, note = {PMID: 36534941}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close https://doi.org/10.1021/acs.inorgchem.2c03599 doi:10.1021/acs.inorgchem.2c03599 Close
34.	Piotr Majek, Grzegorz Górski, Tadeusz Domański, Ireneusz Weymann Hallmarks of Majorana mode leaking into a hybrid double quantum dot Phys. Rev. B, 106 , pp. 155123, 2022. Abstract \| Links \| BibTeX @article{Majek2022c, title = {Hallmarks of Majorana mode leaking into a hybrid double quantum dot}, author = {Piotr Majek and Grzegorz Górski and Tadeusz Domański and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.155123}, doi = {10.1103/PhysRevB.106.155123}, year = {2022}, date = {2022-10-13}, journal = {Phys. Rev. B}, volume = {106}, pages = {155123}, abstract = {We investigate the spectral and transport properties of a double quantum dot laterally attached to a topological superconducting nanowire, hosting the Majorana zero-energy modes. Specifically, we consider a geometry, in which the outer quantum dot is embedded between the external normal and superconducting leads, forming a circuit. First, we derive analytical expressions for the bound states in the case of an uncorrelated system and discuss their signatures in the tunneling spectroscopy. Then, we explore the case of strongly correlated quantum dots by performing the numerical renormalization group calculations, focusing on the interplay and relationship between the leaking Majorana mode and the Kondo states on both quantum dots. Finally, we discuss feasible means to experimentally probe the in-gap quasiparticles by using the Andreev spectroscopy based on the particle-to-hole scattering mechanism.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We investigate the spectral and transport properties of a double quantum dot laterally attached to a topological superconducting nanowire, hosting the Majorana zero-energy modes. Specifically, we consider a geometry, in which the outer quantum dot is embedded between the external normal and superconducting leads, forming a circuit. First, we derive analytical expressions for the bound states in the case of an uncorrelated system and discuss their signatures in the tunneling spectroscopy. Then, we explore the case of strongly correlated quantum dots by performing the numerical renormalization group calculations, focusing on the interplay and relationship between the leaking Majorana mode and the Kondo states on both quantum dots. Finally, we discuss feasible means to experimentally probe the in-gap quasiparticles by using the Andreev spectroscopy based on the particle-to-hole scattering mechanism. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.155123 doi:10.1103/PhysRevB.106.155123 Close
33.	X.-G. Wang, L. Chotorlishvili, G. Tatara, Anna Dyrdał, Guang-hua Guo, V. K. Dugaev, Józef Barnaś, S.S.P. Parkin, A. Ernst Skyrmion lattice hosted in synthetic antiferromagnets and helix modes Phys. Rev. B, 106 , pp. 104424, 2022. Abstract \| Links \| BibTeX @article{Wang2022b, title = {Skyrmion lattice hosted in synthetic antiferromagnets and helix modes}, author = {X.-G. Wang and L. Chotorlishvili and G. Tatara and Anna Dyrdał and Guang-hua Guo and V. K. Dugaev and Józef Barnaś and S.S.P. Parkin and A. Ernst}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.104424}, doi = {10.1103/PhysRevB.106.104424}, year = {2022}, date = {2022-09-20}, journal = {Phys. Rev. B}, volume = {106}, pages = {104424}, abstract = {Thin ferromagnetic films can possess unconventional magnetic properties, opening a new road for using them in spintronic technologies. In the present work exploiting three different methods, we comprehensively analyze phason excitations of a skyrmion lattice in synthetic antiferromagnets. To analyze phason excitations of the skyrmion lattice, we have constructed an analytical model based on three coupled helices and found a linear gapless mode. Micromagnetic simulations also support this result. Moreover, a similar result has been achieved within the rigid skyrmion lattice model based on the coupled Thiele's equations, when the coupling between skyrmions in different layers of the synthetic antiferromagnetic is comparable to or larger than the intralayer coupling. In addition, we also consider the orbital angular momentum and spin pumping current associated with phason excitations. Due to the gapless excitations in the case of skyrmion lattice, the pumping current is nonzero for the arbitrary frequency of pumping microwaves. In the case of individual skyrmions, no current is pumped when microwave frequency is inside the gap of the spectrum of individual skyrmions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Thin ferromagnetic films can possess unconventional magnetic properties, opening a new road for using them in spintronic technologies. In the present work exploiting three different methods, we comprehensively analyze phason excitations of a skyrmion lattice in synthetic antiferromagnets. To analyze phason excitations of the skyrmion lattice, we have constructed an analytical model based on three coupled helices and found a linear gapless mode. Micromagnetic simulations also support this result. Moreover, a similar result has been achieved within the rigid skyrmion lattice model based on the coupled Thiele's equations, when the coupling between skyrmions in different layers of the synthetic antiferromagnetic is comparable to or larger than the intralayer coupling. In addition, we also consider the orbital angular momentum and spin pumping current associated with phason excitations. Due to the gapless excitations in the case of skyrmion lattice, the pumping current is nonzero for the arbitrary frequency of pumping microwaves. In the case of individual skyrmions, no current is pumped when microwave frequency is inside the gap of the spectrum of individual skyrmions. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.104424 doi:10.1103/PhysRevB.106.104424 Close
32.	X.-G. Wang, Guang-hua Guo, Anna Dyrdał, Józef Barnaś, V. K. Dugaev, S. S. P. Parkin, A. Ernst, L. Chotorlishvili Skyrmion Echo in a System of Interacting Skyrmions Phys. Rev. Lett., 129 , pp. 126101, 2022. Abstract \| Links \| BibTeX @article{Wang2022, title = {Skyrmion Echo in a System of Interacting Skyrmions}, author = {X.-G. Wang and Guang-hua Guo and Anna Dyrdał and Józef Barnaś and V. K. Dugaev and S. S. P. Parkin and A. Ernst and L. Chotorlishvili}, url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.126101}, doi = {10.1103/PhysRevLett.129.126101}, year = {2022}, date = {2022-09-14}, journal = {Phys. Rev. Lett.}, volume = {129}, pages = {126101}, abstract = {We consider helical rotation of skyrmions confined in the potentials formed by nanodisks. Based on numerical and analytical calculations we propose the skyrmion echo phenomenon. The physical mechanism of the skyrmion echo formation is also proposed. Because of the distortion of the lattice, impurities, or pinning effect, confined skyrmions experience slightly different local fields, which leads to dephasing of the initial signal. The interaction between skyrmions also can contribute to the dephasing process. However, switching the magnetization direction in the nanodiscs (e.g., by spin transfer torque) also switches the helical rotation of the skyrmions from clockwise to anticlockwise (or vice versa), and this restores the initial signal (which is the essence of skyrmion echo).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We consider helical rotation of skyrmions confined in the potentials formed by nanodisks. Based on numerical and analytical calculations we propose the skyrmion echo phenomenon. The physical mechanism of the skyrmion echo formation is also proposed. Because of the distortion of the lattice, impurities, or pinning effect, confined skyrmions experience slightly different local fields, which leads to dephasing of the initial signal. The interaction between skyrmions also can contribute to the dephasing process. However, switching the magnetization direction in the nanodiscs (e.g., by spin transfer torque) also switches the helical rotation of the skyrmions from clockwise to anticlockwise (or vice versa), and this restores the initial signal (which is the essence of skyrmion echo). Close https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.126101 doi:10.1103/PhysRevLett.129.126101 Close
31.	Anand Manaparambil, Andreas Weichselbaum, Jan von Delft, Ireneusz Weymann Nonequilibrium spintronic transport through Kondo impurities Phys. Rev. B, 106 , pp. 125413, 2022. Abstract \| Links \| BibTeX @article{Manaparambil2022, title = {Nonequilibrium spintronic transport through Kondo impurities}, author = {Anand Manaparambil and Andreas Weichselbaum and Jan von Delft and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.125413}, doi = {10.1103/PhysRevB.106.125413}, year = {2022}, date = {2022-09-14}, journal = {Phys. Rev. B}, volume = {106}, pages = {125413}, abstract = {In this work we analyze the nonequilibrium transport through a quantum impurity (quantum dot or molecule) attached to ferromagnetic leads by using a hybrid numerical renormalization group–time-dependent density matrix renormalization group thermofield quench approach. For this, we study the bias dependence of the differential conductance through the system, which shows a finite zero-bias peak, characteristic of the Kondo resonance and reminiscent of the equilibrium local density of states. In the nonequilibrium settings, the resonance in the differential conductance is also found to decrease with increasing the lead spin polarization. The latter induces an effective exchange field that lifts the spin degeneracy of the dot level. Therefore, as we demonstrate, the Kondo resonance can be restored by counteracting the exchange field with a finite external magnetic field applied to the system. Finally, we investigate the influence of temperature on the nonequilibrium conductance, focusing on the split Kondo resonance. Our work thus provides an accurate quantitative description of the spin-resolved transport properties relevant for quantum dots and molecules embedded in magnetic tunnel junctions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close In this work we analyze the nonequilibrium transport through a quantum impurity (quantum dot or molecule) attached to ferromagnetic leads by using a hybrid numerical renormalization group–time-dependent density matrix renormalization group thermofield quench approach. For this, we study the bias dependence of the differential conductance through the system, which shows a finite zero-bias peak, characteristic of the Kondo resonance and reminiscent of the equilibrium local density of states. In the nonequilibrium settings, the resonance in the differential conductance is also found to decrease with increasing the lead spin polarization. The latter induces an effective exchange field that lifts the spin degeneracy of the dot level. Therefore, as we demonstrate, the Kondo resonance can be restored by counteracting the exchange field with a finite external magnetic field applied to the system. Finally, we investigate the influence of temperature on the nonequilibrium conductance, focusing on the split Kondo resonance. Our work thus provides an accurate quantitative description of the spin-resolved transport properties relevant for quantum dots and molecules embedded in magnetic tunnel junctions. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.125413 doi:10.1103/PhysRevB.106.125413 Close
30.	L. Chotorlishvili, Xi-guang Wang, Anna Dyrdał, Guang-hua Guo, Vitalii K. Dugaev, Józef Barnaś, J. Berakdar Rectification of the spin Seebeck current in noncollinear antiferromagnets Phys. Rev. B, 106 (1), pp. 014417, 2022, ISSN: 2469-9969. Abstract \| Links \| BibTeX @article{Chotorlishvili2022, title = {Rectification of the spin Seebeck current in noncollinear antiferromagnets}, author = {L. Chotorlishvili and Xi-guang Wang and Anna Dyrdał and Guang-hua Guo and Vitalii K. Dugaev and Józef Barnaś and J. Berakdar}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.014417}, doi = {10.1103/PhysRevB.106.014417}, issn = {2469-9969}, year = {2022}, date = {2022-07-25}, journal = {Phys. Rev. B}, volume = {106}, number = {1}, pages = {014417}, abstract = {In the absence of an external magnetic field and a spin-polarized charge current, an antiferromagnetic system supports two degenerate magnon modes. An applied thermal bias activates the magnetic dynamics, leading to a magnon flow from the hot to the cold edge (magnonic spin Seebeck current). Both degenerate bands contribute to the magnon current but the orientations of the magnetic moments underlying the magnons are opposite in different bands. Therefore, while the magnon current is nonzero, the net spin current is zero. To obtain a nonzero net spin current, one needs to apply either a magnetic field or a spin-polarized charge current that lifts the bands' degeneracy. Here, attaching a thermal contact to one edge of a helical nanowire, we study three different magnonic spin currents: (i) the exchange, and (ii) Dzyaloshinskii–Moriya spin currents flowing along the helical nanowire, and (iii) magnonic spin current pumped into the adjacent normal-metal layer. We find that the combination of Dzyaloshinskii–Moriya interaction and external magnetic field substantially enhances the spin current compared to the current generated solely through a magnetic field. Due to nonreciprocal magnons and magnon dichroism effect, the Dzyaloshinskii–Moriya and exchange spin currents show left-right propagation asymmetry, with 20% of current rectification. The spin pumping current shows a slight asymmetry only in the case of a strong Dzyaloshinskii–Moriya interaction. The observed effects are explained in terms of the magnon dispersion relations and the magnon Doppler effect.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close In the absence of an external magnetic field and a spin-polarized charge current, an antiferromagnetic system supports two degenerate magnon modes. An applied thermal bias activates the magnetic dynamics, leading to a magnon flow from the hot to the cold edge (magnonic spin Seebeck current). Both degenerate bands contribute to the magnon current but the orientations of the magnetic moments underlying the magnons are opposite in different bands. Therefore, while the magnon current is nonzero, the net spin current is zero. To obtain a nonzero net spin current, one needs to apply either a magnetic field or a spin-polarized charge current that lifts the bands' degeneracy. Here, attaching a thermal contact to one edge of a helical nanowire, we study three different magnonic spin currents: (i) the exchange, and (ii) Dzyaloshinskii–Moriya spin currents flowing along the helical nanowire, and (iii) magnonic spin current pumped into the adjacent normal-metal layer. We find that the combination of Dzyaloshinskii–Moriya interaction and external magnetic field substantially enhances the spin current compared to the current generated solely through a magnetic field. Due to nonreciprocal magnons and magnon dichroism effect, the Dzyaloshinskii–Moriya and exchange spin currents show left-right propagation asymmetry, with 20% of current rectification. The spin pumping current shows a slight asymmetry only in the case of a strong Dzyaloshinskii–Moriya interaction. The observed effects are explained in terms of the magnon dispersion relations and the magnon Doppler effect. Close https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.014417 doi:10.1103/PhysRevB.106.014417 Close
29.	Mir Ali Jafari, A. A. Kordbacheh, Anna Dyrdał Electronic and magnetic properties of silicene monolayer under bi-axial mechanical strain: First principles study J. Magn. Magn. Mater., 554 , pp. 169260, 2022, ISSN: 0304-8853. Abstract \| Links \| BibTeX @article{Jafari2022b, title = {Electronic and magnetic properties of silicene monolayer under bi-axial mechanical strain: First principles study}, author = {Mir Ali Jafari and A. A. Kordbacheh and Anna Dyrdał}, url = {https://www.sciencedirect.com/science/article/pii/S0304885322002116?via%3Dihub}, doi = {10.1016/j.jmmm.2022.169260}, issn = {0304-8853}, year = {2022}, date = {2022-07-15}, journal = {J. Magn. Magn. Mater.}, volume = {554}, pages = {169260}, abstract = {Mechanical control of electronic and magnetic properties of 2D Van-der-Waals heterostructures gives new possibilities for further development of spintronics and information-related technologies. Using the density functional theory, we investigate the structural, electronic and magnetic properties of silicene monolayer with substituted Chromium atoms and under a small biaxial strain (-6% < e < 8%). Our results indicate that the Cr-doped silicene nanosheets without strain have magnetic metallic, half-metallic or semiconducting properties depending on the type of substitution. We also show that the magnetic moments associated with the monomer and vertical dimer substitutions change very weakly with strain. However, the magnetic moment associated with the horizontal dimer substitution decreases when either compressive or tensile strain is applied to the system. Additionally, we show that the largest semiconductor band-gap is approximately 0.13 eV under zero strain for the vertical Cr-doped silicene. Finally, biaxial compressive strain leads to irregular changes in the magnetic moment for Cr vertical dimer substitution.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Mechanical control of electronic and magnetic properties of 2D Van-der-Waals heterostructures gives new possibilities for further development of spintronics and information-related technologies. Using the density functional theory, we investigate the structural, electronic and magnetic properties of silicene monolayer with substituted Chromium atoms and under a small biaxial strain (-6% < e < 8%). Our results indicate that the Cr-doped silicene nanosheets without strain have magnetic metallic, half-metallic or semiconducting properties depending on the type of substitution. We also show that the magnetic moments associated with the monomer and vertical dimer substitutions change very weakly with strain. However, the magnetic moment associated with the horizontal dimer substitution decreases when either compressive or tensile strain is applied to the system. Additionally, we show that the largest semiconductor band-gap is approximately 0.13 eV under zero strain for the vertical Cr-doped silicene. Finally, biaxial compressive strain leads to irregular changes in the magnetic moment for Cr vertical dimer substitution. Close https://www.sciencedirect.com/science/article/pii/S0304885322002116?via%3Dihub doi:10.1016/j.jmmm.2022.169260 Close
28.	Amir N. Zarezad, Anna Dyrdał Bilinear magnetoresistance in topological insulators: Role of magnetic disorder J. Magn. Magn. Mater., 552 , pp. 169167, 2022, ISSN: 0304-8853. Abstract \| Links \| BibTeX @article{Zarezad2022, title = {Bilinear magnetoresistance in topological insulators: Role of magnetic disorder}, author = {Amir N. Zarezad and Anna Dyrdał}, url = {https://www.sciencedirect.com/science/article/pii/S0304885322001329?via%3Dihub}, doi = {10.1016/j.jmmm.2022.169167}, issn = {0304-8853}, year = {2022}, date = {2022-06-15}, journal = {J. Magn. Magn. Mater.}, volume = {552}, pages = {169167}, abstract = {Bilinear magnetoresistance is a nonlinear transport phenomenon that scales linearly with the electric and magnetic fields, and appears in nonmagnetic systems with strong spin–orbit coupling, such as topological insulators (TIs). Using the semiclassical Boltzmann theory and generalized relaxation time approximation, we consider in detail the bilinear magnetoresistance in an effective model describing surface states of three-dimensional topological insulators. We show that the presence of magnetic impurities remarkably modifies the BMR signal. In general, scattering on magnetic impurities reduces magnitude of BMR. Apart from this, an additional modulation of the angular dependence of BMR appears when the spin-dependent component of the impurity potential dominates the scalar one.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Bilinear magnetoresistance is a nonlinear transport phenomenon that scales linearly with the electric and magnetic fields, and appears in nonmagnetic systems with strong spin–orbit coupling, such as topological insulators (TIs). Using the semiclassical Boltzmann theory and generalized relaxation time approximation, we consider in detail the bilinear magnetoresistance in an effective model describing surface states of three-dimensional topological insulators. We show that the presence of magnetic impurities remarkably modifies the BMR signal. In general, scattering on magnetic impurities reduces magnitude of BMR. Apart from this, an additional modulation of the angular dependence of BMR appears when the spin-dependent component of the impurity potential dominates the scalar one. Close https://www.sciencedirect.com/science/article/pii/S0304885322001329?via%3Dihub doi:10.1016/j.jmmm.2022.169167 Close
27.	Tomasz Ślusarski, Kacper Wrześniewski, Ireneusz Weymann Numerical renormalization group study of the Loschmidt echo in Kondo systems Scientific Reports, 12 , pp. 9799, 2022. Abstract \| Links \| BibTeX @article{Ślusarski2022, title = {Numerical renormalization group study of the Loschmidt echo in Kondo systems}, author = {Tomasz Ślusarski and Kacper Wrześniewski and Ireneusz Weymann}, url = {https://www.nature.com/articles/s41598-022-14108-x}, doi = {10.1038/s41598-022-14108-x}, year = {2022}, date = {2022-06-13}, journal = {Scientific Reports}, volume = {12}, pages = {9799}, abstract = {We study the dynamical properties of the one-channel and two-channel spin-1/2 Kondo models after quenching in Hamiltonian variables. Eigen spectrum of the initial and final Hamiltonians is calculated by using the numerical renormalization group method implemented within the matrix product states formalism. We consider multiple quench protocols in the considered Kondo systems, also in the presence of external magnetic field of different intensities. The main emphasis is put on the analysis of the behavior of the Loschmidt echo L(t), which measures the ability of the system’s revival to its initial state after a quench. We show that the decay of the Loschmidt echo strongly depends on the type of quench and the ground state of the system. For the one-channel Kondo model, we show that L(t) decays as, L(t)∼(t⋅TK)^−1.4, where TK is the Kondo temperature, while for the two-channel Kondo model, we demonstrate that the decay is slower and given by L(t)∼(t⋅TK)^−0.7. In addition, we also determine the dynamical behavior of the impurity’s magnetization, which sheds light on identification of the relevant time scales in the system’s dynamics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close We study the dynamical properties of the one-channel and two-channel spin-1/2 Kondo models after quenching in Hamiltonian variables. Eigen spectrum of the initial and final Hamiltonians is calculated by using the numerical renormalization group method implemented within the matrix product states formalism. We consider multiple quench protocols in the considered Kondo systems, also in the presence of external magnetic field of different intensities. The main emphasis is put on the analysis of the behavior of the Loschmidt echo L(t), which measures the ability of the system’s revival to its initial state after a quench. We show that the decay of the Loschmidt echo strongly depends on the type of quench and the ground state of the system. For the one-channel Kondo model, we show that L(t) decays as, L(t)∼(t⋅TK)^−1.4, where TK is the Kondo temperature, while for the two-channel Kondo model, we demonstrate that the decay is slower and given by L(t)∼(t⋅TK)^−0.7. In addition, we also determine the dynamical behavior of the impurity’s magnetization, which sheds light on identification of the relevant time scales in the system’s dynamics. Close https://www.nature.com/articles/s41598-022-14108-x doi:10.1038/s41598-022-14108-x Close
26.	Vrishali Sonar, Rohan Dehankar, K. P. Vijayalakshmi, Natalio Mingo, Ankita Katre Site-independent strong phonon-vacancy scattering in high-temperature ceramics ZrB2 and HfB2 Phys. Rev. Materials, 6 , pp. 065403, 2022. Abstract \| Links \| BibTeX @article{Sonar2022, title = {Site-independent strong phonon-vacancy scattering in high-temperature ceramics ZrB2 and HfB2}, author = {Vrishali Sonar and Rohan Dehankar and K. P. Vijayalakshmi and Natalio Mingo and Ankita Katre}, url = {https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.6.065403}, doi = {10.1103/PhysRevMaterials.6.065403}, year = {2022}, date = {2022-06-10}, journal = {Phys. Rev. Materials}, volume = {6}, pages = {065403}, abstract = {Similar effects of metal and boron vacancies on phonon scattering and lattice thermal conductivity (κl) of ZrB2 and HfB2 are reported. These defects challenge the conventional understanding that associates larger impacts to bigger defects. We find the underlying reason to be a strong local perturbation caused by boron vacancy that substantially changes the interatomic force constants. In contrast, a long ranged but weaker perturbation is seen in the case of metal vacancy. We show that these behaviors originate from a mixed metallic and covalent bonding nature in the metal diborides. The thermal transport calculations are performed in a complete ab initio framework based on Boltzmann transport equation and density functional theory. Phonon-vacancy scattering is calculated using ab initio Green's function approach. Effects of natural isotopes and grain boundaries on κl are also systematically investigated, however we find an influential role of vacancies to explain large variations seen in the experiments. We further report a two-order of magnitude difference between the amorphous and pure-crystal limits. Our results outline significant material design aspects for these multifunctional high-temperature ceramics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Close Similar effects of metal and boron vacancies on phonon scattering and lattice thermal conductivity (κl) of ZrB2 and HfB2 are reported. These defects challenge the conventional understanding that associates larger impacts to bigger defects. We find the underlying reason to be a strong local perturbation caused by boron vacancy that substantially changes the interatomic force constants. In contrast, a long ranged but weaker perturbation is seen in the case of metal vacancy. We show that these behaviors originate from a mixed metallic and covalent bonding nature in the metal diborides. The thermal transport calculations are performed in a complete ab initio framework based on Boltzmann transport equation and density functional theory. Phonon-vacancy scattering is calculated using ab initio Green's function approach. Effects of natural isotopes and grain boundaries on κl are also systematically investigated, however we find an influential role of vacancies to explain large variations seen in the experiments. We further report a two-order of magnitude difference between the amorphous and pure-crystal limits. Our results outline significant material design aspects for these multifunctional high-temperature ceramics. Close https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.6.065403 doi:10.1103/PhysRevMaterials.6.065403 Close

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