List of publications
Department of Mesoscopic Physics
Department of Nonlinear Optics
Department of Physics of Nanostructures
Department of Theory of Condensed Matter
2022 |
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| 86. | Huan-Yu Ku, Josef Kadlec, Antonín Černoch, Marco Túlio Quintino, Wenbin Zhou, Karel Lemr, Neill Lambert, Adam Miranowicz, Shin-Liang Chen, Franco Nori, Yueh-Nan Chen Quantifying Quantumness of Channels Without Entanglement PRX Quantum, 3 , pp. 020338, 2022. @article{Ku2022, title = {Quantifying Quantumness of Channels Without Entanglement}, author = {Huan-Yu Ku and Josef Kadlec and Antonín Černoch and Marco Túlio Quintino and Wenbin Zhou and Karel Lemr and Neill Lambert and Adam Miranowicz and Shin-Liang Chen and Franco Nori and Yueh-Nan Chen}, url = {https://journals.aps.org/prxquantum/abstract/10.1103/PRXQuantum.3.020338}, doi = {10.1103/PRXQuantum.3.020338}, year = {2022}, date = {2022-05-19}, journal = {PRX Quantum}, volume = {3}, pages = {020338}, abstract = {Quantum channels breaking entanglement, incompatibility, or nonlocality are defined as such because they are not useful for entanglement-based, one-sided device-independent, or device-independent quantum-information processing, respectively. Here, we show that such breaking channels are related to complementary tests of macrorealism, i.e., temporal separability, channel unsteerability, temporal unsteerability, and the temporal Bell inequality. To demonstrate this we first define a steerability-breaking channel, which is conceptually similar to entanglement and nonlocality-breaking channels and prove that it is identical to an incompatibility-breaking channel. A hierarchy of quantum nonbreaking channels is derived, akin to the existing hierarchy relations for temporal and spatial quantum correlations. We then introduce the concept of channels that break temporal correlations, explain how they are related to the standard breaking channels, and prove the following results. (1) A robustness-based measure for non-entanglement-breaking channels can be probed by temporal nonseparability. (2) A non-steerability-breaking channel can be quantified by channel steering. (3) Temporal steerability and nonmacrorealism can be used for, respectively, distinguishing unital steerability-breaking channels and nonlocality-breaking channels for a maximally entangled state. Finally, a two-dimensional depolarizing channel is experimentally implemented as a proof-of-principle example to demonstrate the hierarchy relation of nonbreaking channels using temporal quantum correlations.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Quantum channels breaking entanglement, incompatibility, or nonlocality are defined as such because they are not useful for entanglement-based, one-sided device-independent, or device-independent quantum-information processing, respectively. Here, we show that such breaking channels are related to complementary tests of macrorealism, i.e., temporal separability, channel unsteerability, temporal unsteerability, and the temporal Bell inequality. To demonstrate this we first define a steerability-breaking channel, which is conceptually similar to entanglement and nonlocality-breaking channels and prove that it is identical to an incompatibility-breaking channel. A hierarchy of quantum nonbreaking channels is derived, akin to the existing hierarchy relations for temporal and spatial quantum correlations. We then introduce the concept of channels that break temporal correlations, explain how they are related to the standard breaking channels, and prove the following results. (1) A robustness-based measure for non-entanglement-breaking channels can be probed by temporal nonseparability. (2) A non-steerability-breaking channel can be quantified by channel steering. (3) Temporal steerability and nonmacrorealism can be used for, respectively, distinguishing unital steerability-breaking channels and nonlocality-breaking channels for a maximally entangled state. Finally, a two-dimensional depolarizing channel is experimentally implemented as a proof-of-principle example to demonstrate the hierarchy relation of nonbreaking channels using temporal quantum correlations. |
| 85. | Jingyuan Zhou, Mateusz Zelent, Zhaochu Luo, Valerio Scagnoli, Maciej Krawczyk, Laura J Heyderman, Susmita Saha Phys. Rev. B, 105 , pp. 174415, 2022. @article{PhysRevB.105.174415, title = {Precessional dynamics of geometrically scaled magnetostatic spin waves in two-dimensional magnonic fractals}, author = {Jingyuan Zhou and Mateusz Zelent and Zhaochu Luo and Valerio Scagnoli and Maciej Krawczyk and Laura J Heyderman and Susmita Saha}, url = {https://link.aps.org/doi/10.1103/PhysRevB.105.174415}, doi = {10.1103/PhysRevB.105.174415}, year = {2022}, date = {2022-05-13}, journal = {Phys. Rev. B}, volume = {105}, pages = {174415}, publisher = {American Physical Society}, abstract = {The control of spin waves in periodic magnetic structures has facilitated the realization of many functional magnonic devices, such as band stop filters and magnonic transistors, where the geometry of the crystal structure plays an important role. Here, we report on the magnetostatic mode formation in an artificial magnetic structure, going beyond the crystal geometry to a fractal structure, where the mode formation is related to the geometric scaling of the fractal structure. Specifically, the precessional dynamics was measured in samples with structures going from simple geometric structures toward a Sierpinski carpet and a Sierpinski triangle. The experimentally observed evolution of the precessional motion could be linked to the progression in the geometric structures that results in a modification of the demagnetizing field. Furthermore, we have found sets of modes at the ferromagnetic resonance frequency that form a scaled spatial distribution following the geometric scaling. Based on this, we have determined the two conditions for such mode formation to occur. One condition is that the associated magnetic boundaries must scale accordingly, and the other condition is that the region where the mode occurs must not coincide with the regions for the edge modes. This established relationship between the fractal geometry and the mode formation in magnetic fractals provides guiding principles for their use in magnonics applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The control of spin waves in periodic magnetic structures has facilitated the realization of many functional magnonic devices, such as band stop filters and magnonic transistors, where the geometry of the crystal structure plays an important role. Here, we report on the magnetostatic mode formation in an artificial magnetic structure, going beyond the crystal geometry to a fractal structure, where the mode formation is related to the geometric scaling of the fractal structure. Specifically, the precessional dynamics was measured in samples with structures going from simple geometric structures toward a Sierpinski carpet and a Sierpinski triangle. The experimentally observed evolution of the precessional motion could be linked to the progression in the geometric structures that results in a modification of the demagnetizing field. Furthermore, we have found sets of modes at the ferromagnetic resonance frequency that form a scaled spatial distribution following the geometric scaling. Based on this, we have determined the two conditions for such mode formation to occur. One condition is that the associated magnetic boundaries must scale accordingly, and the other condition is that the region where the mode occurs must not coincide with the regions for the edge modes. This established relationship between the fractal geometry and the mode formation in magnetic fractals provides guiding principles for their use in magnonics applications. |
| 84. | Piotr Majek, Ireneusz Weymann Majorana-Kondo competition in a cross-shaped double quantum dot-topological superconductor system Journal of Magnetism and Magnetic Materials, (549), pp. 168935, 2022. @article{Majek2022, title = {Majorana-Kondo competition in a cross-shaped double quantum dot-topological superconductor system}, author = {Piotr Majek and Ireneusz Weymann}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0304885321011331}, doi = {10.1016/j.jmmm.2021.168935}, year = {2022}, date = {2022-05-01}, journal = {Journal of Magnetism and Magnetic Materials}, number = {549}, pages = {168935}, abstract = {We examine the transport properties of a double quantum dot system coupled to a topological superconducting nanowire hosting Majorana quasiparticles at its ends, with the central quantum dot attached to the left and right leads. We focus on the behavior of the local density of states and the linear conductance, calculated with the aid of the numerical renormalization group method, to describe the influence of the Majorana coupling on the low-temperature transport properties induced by the Kondo correlations. In particular, we show that the presence of Majorana quasiparticles in the system affects both the spin-up and spin-down transport channels, affecting the energy scales associated with the first-stage and second-stage Kondo temperatures, respectively, and modifying the low-energy behavior of the system.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We examine the transport properties of a double quantum dot system coupled to a topological superconducting nanowire hosting Majorana quasiparticles at its ends, with the central quantum dot attached to the left and right leads. We focus on the behavior of the local density of states and the linear conductance, calculated with the aid of the numerical renormalization group method, to describe the influence of the Majorana coupling on the low-temperature transport properties induced by the Kondo correlations. In particular, we show that the presence of Majorana quasiparticles in the system affects both the spin-up and spin-down transport channels, affecting the energy scales associated with the first-stage and second-stage Kondo temperatures, respectively, and modifying the low-energy behavior of the system. |
| 83. | Paweł Gruszecki, Konstantin Y Guslienko, Igor L Lyubchanskii, Maciej Krawczyk Inelastic Spin-Wave Beam Scattering by Edge-Localized Spin Waves in a Ferromagnetic Thin Film Phys. Rev. Applied, 17 , pp. 044038, 2022. @article{PhysRevApplied.17.044038, title = {Inelastic Spin-Wave Beam Scattering by Edge-Localized Spin Waves in a Ferromagnetic Thin Film}, author = {Paweł Gruszecki and Konstantin Y Guslienko and Igor L Lyubchanskii and Maciej Krawczyk}, url = {https://link.aps.org/doi/10.1103/PhysRevApplied.17.044038}, doi = {10.1103/PhysRevApplied.17.044038}, year = {2022}, date = {2022-04-20}, journal = {Phys. Rev. Applied}, volume = {17}, pages = {044038}, publisher = {American Physical Society}, abstract = {Spin waves are promising chargeless information carriers for the future, energetically efficient beyond CMOS systems. Among many advantages are the ease of achieving nonlinearity, the variety of possible interactions, and excitation types. Although the rapidly developing magnonic research has already yielded impressive realizations, multimode nonlinear effects, particularly with propagating waves and their nanoscale realizations, are still an open research problem.We theoretically study the dynamic interactions of spin waves confined to the edge of a thin ferromagnetic film with the spin-wave beam incident at this edge. We find inelastically scattered spin-wave beams at frequencies increased and decreased by the frequency of the edge spin-wave relative to the specularly reflected beam. We observe a strong dependence of the angular shift of the inelastic scattered spin-wave beam on the edge-mode frequency, which allows us to propose a magnonic demultiplexing of the signal encoded in spin waves propagating along the edge. Since dynamic magnetostatic interactions, which are ubiquitous in the spin-wave dynamics, are decisive in this process, this indicates the possibility of implementing the presented effects in other configurations and their use in magnonic systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Spin waves are promising chargeless information carriers for the future, energetically efficient beyond CMOS systems. Among many advantages are the ease of achieving nonlinearity, the variety of possible interactions, and excitation types. Although the rapidly developing magnonic research has already yielded impressive realizations, multimode nonlinear effects, particularly with propagating waves and their nanoscale realizations, are still an open research problem.We theoretically study the dynamic interactions of spin waves confined to the edge of a thin ferromagnetic film with the spin-wave beam incident at this edge. We find inelastically scattered spin-wave beams at frequencies increased and decreased by the frequency of the edge spin-wave relative to the specularly reflected beam. We observe a strong dependence of the angular shift of the inelastic scattered spin-wave beam on the edge-mode frequency, which allows us to propose a magnonic demultiplexing of the signal encoded in spin waves propagating along the edge. Since dynamic magnetostatic interactions, which are ubiquitous in the spin-wave dynamics, are decisive in this process, this indicates the possibility of implementing the presented effects in other configurations and their use in magnonic systems. |
| 82. | A K Dhiman, R Gieniusz, Paweł Gruszecki, J Kisielewski, M Matczak, Z Kurant, I Sveklo, U Guzowska, M Tekielak, F Stobiecki, A Maziewski Magnetization statics and dynamics in (Ir/Co/Pt)6 multilayers with Dzyaloshinskii–Moriya interaction AIP Advances, 12 (4), pp. 045007, 2022. @article{Dhiman2022DMI, title = {Magnetization statics and dynamics in (Ir/Co/Pt)6 multilayers with Dzyaloshinskii–Moriya interaction}, author = {A K Dhiman and R Gieniusz and Paweł Gruszecki and J Kisielewski and M Matczak and Z Kurant and I Sveklo and U Guzowska and M Tekielak and F Stobiecki and A Maziewski}, doi = {https://doi.org/10.1063/9.0000339}, year = {2022}, date = {2022-04-04}, urldate = {2022-04-04}, journal = {AIP Advances}, volume = {12}, number = {4}, pages = {045007}, abstract = {Magnetic multilayers of (Ir/Co/Pt)6 with interfacial Dzyaloshinskii-Moriya interaction (IDMI) were deposited by magnetron sputtering with Co thickness d=1.8 nm. Exploiting magneto-optical Kerr effect in longitudinal mode microscopy, magnetic force microscopy, and vibrating sample magnetometry, the magnetic field-driven evolution of domain structures and magnetization hysteresis loops have been studied. The existence of weak stripe domains structure was deduced – tens micrometers size domains with in-plane “core” magnetization modulated by hundred of nanometers domains with out-of-plane magnetization. Micromagnetic simulations interpreted such magnetization distribution. Quantitative evaluation of IDMI was carried out using Brillouin light scattering (BLS) spectroscopy as the difference between Stokes and anti-Stokes peak frequencies Δf. Due to the additive nature of IDMI, the asymmetric combination of Ir and Pt covers led to large values of effective IDMI energy density Deff. It was found that Stokes and anti-Stokes frequencies as well as Δf, measured as a function of in-plane applied magnetic field, show hysteresis. These results are explained under the consideration of the influence of IDMI on the dynamics of the in-plane magnetized “core” with weak stripe domains}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnetic multilayers of (Ir/Co/Pt)6 with interfacial Dzyaloshinskii-Moriya interaction (IDMI) were deposited by magnetron sputtering with Co thickness d=1.8 nm. Exploiting magneto-optical Kerr effect in longitudinal mode microscopy, magnetic force microscopy, and vibrating sample magnetometry, the magnetic field-driven evolution of domain structures and magnetization hysteresis loops have been studied. The existence of weak stripe domains structure was deduced – tens micrometers size domains with in-plane “core” magnetization modulated by hundred of nanometers domains with out-of-plane magnetization. Micromagnetic simulations interpreted such magnetization distribution. Quantitative evaluation of IDMI was carried out using Brillouin light scattering (BLS) spectroscopy as the difference between Stokes and anti-Stokes peak frequencies Δf. Due to the additive nature of IDMI, the asymmetric combination of Ir and Pt covers led to large values of effective IDMI energy density Deff. It was found that Stokes and anti-Stokes frequencies as well as Δf, measured as a function of in-plane applied magnetic field, show hysteresis. These results are explained under the consideration of the influence of IDMI on the dynamics of the in-plane magnetized “core” with weak stripe domains |
| 81. | Chia-Yi Ju, Adam Miranowicz, Fabrizio Minganti, Chuan-Tsung Chan, Guang-Yin Chen, Franco Nori Phys. Rev. Research, 4 , pp. 023070, 2022. @article{Ju22prr, title = {Einstein's quantum elevator: Hermitization of non-Hermitian Hamiltonians via a generalized vielbein formalism}, author = {Chia-Yi Ju and Adam Miranowicz and Fabrizio Minganti and Chuan-Tsung Chan and Guang-Yin Chen and Franco Nori}, url = {https://link.aps.org/doi/10.1103/PhysRevResearch.4.023070}, doi = {10.1103/PhysRevResearch.4.023070}, year = {2022}, date = {2022-04-01}, journal = {Phys. Rev. Research}, volume = {4}, pages = {023070}, publisher = {American Physical Society}, abstract = {The formalism for non-Hermitian quantum systems sometimes blurs the underlying physics. We present a systematic study of the vielbeinlike formalism which transforms the Hilbert space bundles of non-Hermitian systems into the conventional ones, rendering the induced Hamiltonian to be Hermitian. In other words, any non-Hermitian Hamiltonian can be “transformed” into a Hermitian one without altering the physics. Thus we show how to find a reference frame (corresponding to Einstein's quantum elevator) in which a non-Hermitian system, equipped with a nontrivial Hilbert space metric, reduces to a Hermitian system within the standard formalism of quantum mechanics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The formalism for non-Hermitian quantum systems sometimes blurs the underlying physics. We present a systematic study of the vielbeinlike formalism which transforms the Hilbert space bundles of non-Hermitian systems into the conventional ones, rendering the induced Hamiltonian to be Hermitian. In other words, any non-Hermitian Hamiltonian can be “transformed” into a Hermitian one without altering the physics. Thus we show how to find a reference frame (corresponding to Einstein's quantum elevator) in which a non-Hermitian system, equipped with a nontrivial Hilbert space metric, reduces to a Hermitian system within the standard formalism of quantum mechanics. |
| 80. | Piotr Trocha, Emil Siuda Spin-thermoelectric effects in a quantum dot hybrid system with magnetic insulator Scientific Reports, 12 (5348), 2022. @article{Trocha2022c, title = {Spin-thermoelectric effects in a quantum dot hybrid system with magnetic insulator}, author = {Piotr Trocha and Emil Siuda}, url = {https://www.nature.com/articles/s41598-022-09105-z}, doi = {10.1038/s41598-022-09105-z}, year = {2022}, date = {2022-03-30}, journal = {Scientific Reports}, volume = {12}, number = {5348}, abstract = {We investigate spin thermoelectric properties of a hybrid system consisting of a single-level quantum dot attached to magnetic insulator and metal electrodes. Magnetic insulator is assumed to be of ferromagnetic type and is a source of magnons, whereas metallic lead is reservoir of electrons. The temperature gradient set between the magnetic insulator and metallic electrodes induces the spin current flowing through the system. The generated spin current of magnonic (electric) type is converted to electric (magnonic) spin current by means of quantum dot. Expanding spin and heat currents flowing through the system, up to linear order, we introduce basic spin thermoelectric coefficients including spin conductance, spin Seebeck and spin Peltier coefficients and heat conductance. We analyse the spin thermoelectric properties of the system in two cases: in the large ondot Coulomb repulsion limit and when these interactions are finite.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate spin thermoelectric properties of a hybrid system consisting of a single-level quantum dot attached to magnetic insulator and metal electrodes. Magnetic insulator is assumed to be of ferromagnetic type and is a source of magnons, whereas metallic lead is reservoir of electrons. The temperature gradient set between the magnetic insulator and metallic electrodes induces the spin current flowing through the system. The generated spin current of magnonic (electric) type is converted to electric (magnonic) spin current by means of quantum dot. Expanding spin and heat currents flowing through the system, up to linear order, we introduce basic spin thermoelectric coefficients including spin conductance, spin Seebeck and spin Peltier coefficients and heat conductance. We analyse the spin thermoelectric properties of the system in two cases: in the large ondot Coulomb repulsion limit and when these interactions are finite. |
| 79. | Mir Ali Jafari, Anna Dyrdał Molecules, 27 (7), pp. 2228, 2022, ISSN: 1420-3049. @article{Jafari2022c, title = {First Principle Study on Electronic and Transport Properties of Finite-Length Nanoribbons and Nanodiscs for Selected Two-Dimensional Materials}, author = {Mir Ali Jafari and Anna Dyrdał}, url = {https://www.mdpi.com/1420-3049/27/7/2228}, doi = {10.3390/molecules27072228}, issn = {1420-3049}, year = {2022}, date = {2022-03-29}, journal = {Molecules}, volume = {27}, number = {7}, pages = {2228}, abstract = {Using the density functional theory, we calculate electronic states of various nanoribbons and nanodiscs formed from selected two-dimensional materials, such as graphene, silicene, and hexagonal boron nitride. The main objective of the analysis is a search for zero-energy states in such systems, which is an important issue as their presence indicates certain topological properties associated with chirality. The analysis is also supported by calculating transport properties.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Using the density functional theory, we calculate electronic states of various nanoribbons and nanodiscs formed from selected two-dimensional materials, such as graphene, silicene, and hexagonal boron nitride. The main objective of the analysis is a search for zero-energy states in such systems, which is an important issue as their presence indicates certain topological properties associated with chirality. The analysis is also supported by calculating transport properties. |
| 78. | Yi-Hao Kang, Ye-Hong Chen, Xin Wang, Jie Song, Yan Xia, Adam Miranowicz, Shi-Biao Zheng, Franco Nori Phys. Rev. Research, 4 , pp. 013233, 2022. @article{Kang2022, title = {Nonadiabatic geometric quantum computation with cat-state qubits via invariant-based reverse engineering}, author = {Yi-Hao Kang and Ye-Hong Chen and Xin Wang and Jie Song and Yan Xia and Adam Miranowicz and Shi-Biao Zheng and Franco Nori}, url = {https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.4.013233}, doi = {10.1103/PhysRevResearch.4.013233}, year = {2022}, date = {2022-03-28}, journal = {Phys. Rev. Research}, volume = {4}, pages = {013233}, abstract = {We propose a protocol to realize nonadiabatic geometric quantum computation of small-amplitude Schrödinger cat qubits via invariant-based reverse engineering. We consider a system with a two-photon driven Kerr nonlinearity, which can generate a pair of dressed even and odd coherent states (i.e., Schrödinger cat states) for fault-tolerant quantum computations. An additional coherent field is applied to linearly drive a cavity mode, to induce oscillations between dressed cat states. By designing this linear drive with invariant-based reverse engineering, we show how to implement nonadiabatic geometric quantum computation with cat qubits. The performance of the protocol is estimated by taking into account the influence of systematic errors, additive white Gaussian noise, 1/f noise, and decoherence including photon loss and dephasing. Numerical results demonstrate that our protocol is robust against these negative factors. Therefore, this protocol may provide a feasible method for nonadiabatic geometric quantum computation in bosonic systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose a protocol to realize nonadiabatic geometric quantum computation of small-amplitude Schrödinger cat qubits via invariant-based reverse engineering. We consider a system with a two-photon driven Kerr nonlinearity, which can generate a pair of dressed even and odd coherent states (i.e., Schrödinger cat states) for fault-tolerant quantum computations. An additional coherent field is applied to linearly drive a cavity mode, to induce oscillations between dressed cat states. By designing this linear drive with invariant-based reverse engineering, we show how to implement nonadiabatic geometric quantum computation with cat qubits. The performance of the protocol is estimated by taking into account the influence of systematic errors, additive white Gaussian noise, 1/f noise, and decoherence including photon loss and dephasing. Numerical results demonstrate that our protocol is robust against these negative factors. Therefore, this protocol may provide a feasible method for nonadiabatic geometric quantum computation in bosonic systems. |
| 77. | Kacper Wrześniewski, Ireneusz Weymann, Nicholas Sedlmayr, Tadeusz Domański Dynamical quantum phase transitions in a mesoscopic superconducting system Phys. Rev. B, 105 , pp. 094514, 2022. @article{Wrześniewski2022c, title = {Dynamical quantum phase transitions in a mesoscopic superconducting system}, author = {Kacper Wrześniewski and Ireneusz Weymann and Nicholas Sedlmayr and Tadeusz Domański}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.105.094514}, doi = {10.1103/PhysRevB.105.094514}, year = {2022}, date = {2022-03-25}, journal = {Phys. Rev. B}, volume = {105}, pages = {094514}, abstract = {We inspect the signatures of dynamical quantum phase transitions driven by quantum quenches acting on a correlated quantum dot embedded between superconducting and metallic reservoirs. Under stationary conditions, the proximity-induced electron pairing, competing with strong Coulomb repulsion, enforces the quantum dot to be either in the singly occupied or BCS-type ground state, depending on its energy level and coupling to the superconducting lead. By means of the time-dependent numerical renormalization group approach, we study the system's time evolution upon traversing the phase boundary between these two states, examining the Loschmidt echo and revealing nonanalytic features in the low-energy return rate, which signal dynamical quantum phase transitions. We also show that these phase transitions are accompanied by the corresponding local extrema in the pairing correlation function and dot's occupation. Since the proposed quench protocols can be realized in a controllable manner, the detection of this dynamical singlet-doublet phase transition should be feasible by performing tunneling spectroscopy measurements.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We inspect the signatures of dynamical quantum phase transitions driven by quantum quenches acting on a correlated quantum dot embedded between superconducting and metallic reservoirs. Under stationary conditions, the proximity-induced electron pairing, competing with strong Coulomb repulsion, enforces the quantum dot to be either in the singly occupied or BCS-type ground state, depending on its energy level and coupling to the superconducting lead. By means of the time-dependent numerical renormalization group approach, we study the system's time evolution upon traversing the phase boundary between these two states, examining the Loschmidt echo and revealing nonanalytic features in the low-energy return rate, which signal dynamical quantum phase transitions. We also show that these phase transitions are accompanied by the corresponding local extrema in the pairing correlation function and dot's occupation. Since the proposed quench protocols can be realized in a controllable manner, the detection of this dynamical singlet-doublet phase transition should be feasible by performing tunneling spectroscopy measurements. |
| 76. | M Baranowski, Sławomir Mamica Resonance modes of periodically structuralized microwave magnetic elements Journal of Magnetism and Magnetic Materials, 553 , pp. 169261, 2022, ISSN: 0304-8853. @article{BARANOWSKI2022169261, title = {Resonance modes of periodically structuralized microwave magnetic elements}, author = {M Baranowski and Sławomir Mamica}, url = {https://www.sciencedirect.com/science/article/pii/S0304885322002128}, doi = {https://doi.org/10.1016/j.jmmm.2022.169261}, issn = {0304-8853}, year = {2022}, date = {2022-03-16}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {553}, pages = {169261}, abstract = {Here we consider a flower-like structure of a resonator consisting of six elliptical elements, referred to as petals, made from a magnetic material. The petals are positioned with their centres at the corners of a regular hexagon. Using numerical simulations (CST Studio) we examine the effect of different radial orientations of petals. We study resonance modes with a specific distribution of the electromagnetic field within the resonator as well as the effect of the rotation of petals on the field distribution. The mode character is crucial to understand the behaviour of the frequency spectrum. E.g., the rotation of petals influences significantly the frequency of the lowest mode only, while the other frequencies are almost unchanged and this effect is directly related to the profiles of modes. The system studied is a promising candidate for a tuneable component of an integrated detection system.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Here we consider a flower-like structure of a resonator consisting of six elliptical elements, referred to as petals, made from a magnetic material. The petals are positioned with their centres at the corners of a regular hexagon. Using numerical simulations (CST Studio) we examine the effect of different radial orientations of petals. We study resonance modes with a specific distribution of the electromagnetic field within the resonator as well as the effect of the rotation of petals on the field distribution. The mode character is crucial to understand the behaviour of the frequency spectrum. E.g., the rotation of petals influences significantly the frequency of the lowest mode only, while the other frequencies are almost unchanged and this effect is directly related to the profiles of modes. The system studied is a promising candidate for a tuneable component of an integrated detection system. |
| 75. | Patrycja Tulewicz, Kacper Wrześniewski, Ireneusz Weymann Spintronic transport through a double quantum dot-based spin valve with noncollinear magnetizations Journal of Magnetism and Magnetic Materials, 546 , pp. 168788, 2022. @article{Tulewicz2022, title = {Spintronic transport through a double quantum dot-based spin valve with noncollinear magnetizations}, author = {Patrycja Tulewicz and Kacper Wrześniewski and Ireneusz Weymann}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321010118}, doi = {10.1016/j.jmmm.2021.168788}, year = {2022}, date = {2022-03-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {546}, pages = {168788}, abstract = {We study the magnetoresistive properties of a spin valve based on a double quantum dot attached to ferromagnetic leads with noncollinear alignment of magnetic moments. It is assumed that each dot is strongly coupled to its own ferromagnetic electrode, while the hopping between the dots is relatively weak. The calculations are performed by using the perturbation theory in the coupling between the dots, while the local density of states of a quantum dot attached to a given external lead is determined with the aid of the numerical renormalization group method. We demonstrate that the examined device can exhibit considerable positive or inverse tunnel magnetoresistance. It can be also a source of highly spin-polarized current. Importantly, the spin-resolved transport properties can be controlled by gate and bias voltages and depend on the angle between the magnetizations of the ferromagnets.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study the magnetoresistive properties of a spin valve based on a double quantum dot attached to ferromagnetic leads with noncollinear alignment of magnetic moments. It is assumed that each dot is strongly coupled to its own ferromagnetic electrode, while the hopping between the dots is relatively weak. The calculations are performed by using the perturbation theory in the coupling between the dots, while the local density of states of a quantum dot attached to a given external lead is determined with the aid of the numerical renormalization group method. We demonstrate that the examined device can exhibit considerable positive or inverse tunnel magnetoresistance. It can be also a source of highly spin-polarized current. Importantly, the spin-resolved transport properties can be controlled by gate and bias voltages and depend on the angle between the magnetizations of the ferromagnets. |
| 74. | Piotr Busz, Damian Tomaszewski, Jan Martinek Exchange field determination in a quantum dot spin valve by the spin dynamics Journal of Magnetism and Magnetic Materials, 546 , pp. 168831, 2022. @article{Busz2022, title = {Exchange field determination in a quantum dot spin valve by the spin dynamics}, author = {Piotr Busz and Damian Tomaszewski and Jan Martinek}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321010428}, doi = {10.1016/j.jmmm.2021.168831}, year = {2022}, date = {2022-03-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {546}, pages = {168831}, abstract = {We develop the theory of the electron transport through quantum dot weakly coupled to ferromagnetic leads with noncollinear magnetization directions, that has been studied in recent experiments. One can observe much richer transport behavior of the canted quantum dot spin valves, as compared to single magnetic tunnel junctions, that relies on the possibility to generate a nonequilibrium accumulated spin on the quantum dot and the presence of the exchange interaction between dot and electrodes, depending on system parameters such as gate and bias voltages, the charging energy, an asymmetry of the tunnel couplings, and the external magnetic field. We demonstrate that one can extract information about spin dynamics on quantum dot from the dc current–voltage characteristic even at the linear response, and detect the exchange field similarly to the FMR (ferromagnetic resonance) experiment. This exchange field can be widely used in nano-spinelectronics, as a local field controlled by the gate or bias voltages also at high temperatures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We develop the theory of the electron transport through quantum dot weakly coupled to ferromagnetic leads with noncollinear magnetization directions, that has been studied in recent experiments. One can observe much richer transport behavior of the canted quantum dot spin valves, as compared to single magnetic tunnel junctions, that relies on the possibility to generate a nonequilibrium accumulated spin on the quantum dot and the presence of the exchange interaction between dot and electrodes, depending on system parameters such as gate and bias voltages, the charging energy, an asymmetry of the tunnel couplings, and the external magnetic field. We demonstrate that one can extract information about spin dynamics on quantum dot from the dc current–voltage characteristic even at the linear response, and detect the exchange field similarly to the FMR (ferromagnetic resonance) experiment. This exchange field can be widely used in nano-spinelectronics, as a local field controlled by the gate or bias voltages also at high temperatures. |
| 73. | Piotr Trocha, Emil Siuda, Ireneusz Weymann Spin-polarized transport in quadruple quantum dots attached to ferromagnetic leads Journal of Magnetism and Magnetic Materials, 546 (168835), 2022. @article{Trocha2022b, title = {Spin-polarized transport in quadruple quantum dots attached to ferromagnetic leads}, author = {Piotr Trocha and Emil Siuda and Ireneusz Weymann}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321010453}, doi = {10.1016/j.jmmm.2021.168835}, year = {2022}, date = {2022-03-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {546}, number = {168835}, abstract = {Motivated by the experimental evidence of the Nagaoka ferromagnetism in quantum dot systems by Dehollain et al. (2020), we search for possible confirmation of such kind of ferromagnetism by analyzing the spin-resolved transport properties of a quadruple quantum dot system focusing on the linear response regime. In particular, we consider four quantum dots arranged in a two-by-two square lattice, coupled to external ferromagnetic source and drain electrodes. Turning on and off the specific conditions for the Nagaoka ferromagnetism to occur by changing the value of the intra-dot Coulomb interactions, we determine the transport coefficients, including the linear conductance, tunnel magnetoresistance and current spin polarization. We show that a sign change of the current spin polarization may be an indication of a ferromagnetic order of Nagaoka type which develops in the system.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Motivated by the experimental evidence of the Nagaoka ferromagnetism in quantum dot systems by Dehollain et al. (2020), we search for possible confirmation of such kind of ferromagnetism by analyzing the spin-resolved transport properties of a quadruple quantum dot system focusing on the linear response regime. In particular, we consider four quantum dots arranged in a two-by-two square lattice, coupled to external ferromagnetic source and drain electrodes. Turning on and off the specific conditions for the Nagaoka ferromagnetism to occur by changing the value of the intra-dot Coulomb interactions, we determine the transport coefficients, including the linear conductance, tunnel magnetoresistance and current spin polarization. We show that a sign change of the current spin polarization may be an indication of a ferromagnetic order of Nagaoka type which develops in the system. |
| 72. | Wojciech Rudziński Effect of single-ion anisotropy on magnons in the VSe2 bilayer antiferromagnet J. Magn. Magn. Mater., 546 , pp. 168687, 2022, ISSN: 0304-8853. @article{Rudziński2022, title = {Effect of single-ion anisotropy on magnons in the VSe2 bilayer antiferromagnet}, author = {Wojciech Rudziński}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009239?via%3Dihub}, doi = {10.1016/j.jmmm.2021.168687}, issn = {0304-8853}, year = {2022}, date = {2022-03-15}, journal = {J. Magn. Magn. Mater.}, volume = {546}, pages = {168687}, abstract = {Spectrum of spin waves (magnons) in the two-dimensional bilayer antiferromagnet based on the VSe 2 is studied theoretically. The vanadium atoms within individual layers are coupled ferromagnetically, while the exchange coupling between V atoms located in different planes is antiferromagnetic. The magnon dispersion relation and its dependence on magnetic anisotropy is analyzed in the regime of weak external magnetic field. The spin-wave spectra are derived within the spin-wave theory of antiferromagnets in terms of the Holstein–Primakoff transformation combined with the Bogolubov diagonalization scheme. The magnon dispersion features are discussed in case of the T-type stacking of the VSe2 bilayer.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Spectrum of spin waves (magnons) in the two-dimensional bilayer antiferromagnet based on the VSe 2 is studied theoretically. The vanadium atoms within individual layers are coupled ferromagnetically, while the exchange coupling between V atoms located in different planes is antiferromagnetic. The magnon dispersion relation and its dependence on magnetic anisotropy is analyzed in the regime of weak external magnetic field. The spin-wave spectra are derived within the spin-wave theory of antiferromagnets in terms of the Holstein–Primakoff transformation combined with the Bogolubov diagonalization scheme. The magnon dispersion features are discussed in case of the T-type stacking of the VSe2 bilayer. |
| 71. | Mir Ali Jafari, Małgorzata Wawrzyniak-Adamczewska, Stefan Stagraczyński, Anna Dyrdał, Józef Barnaś Spin valve effect in two-dimensional VSe2 system J. Magn. Magn. Mater., 548 , pp. 168921, 2022, ISSN: 0304-8853. @article{Jafari2022, title = {Spin valve effect in two-dimensional VSe2 system}, author = {Mir Ali Jafari and Małgorzata Wawrzyniak-Adamczewska and Stefan Stagraczyński and Anna Dyrdał and Józef Barnaś}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321011215?via%3Dihub}, doi = {10.1016/j.jmmm.2021.168921}, issn = {0304-8853}, year = {2022}, date = {2022-03-15}, journal = {J. Magn. Magn. Mater.}, volume = {548}, pages = {168921}, abstract = {Vanadium based dichalcogenides, VSe2, are two-dimensional materials in which magnetic Vanadium atoms are arranged in a hexagonal lattice and are coupled ferromagnetically within the plane. However, adjacent atomic planes are coupled antiferromagnetically. This provides new and interesting opportunities for application in spintronics and data storage and processing technologies. A spin valve magnetoresistance may be achieved when magnetic moments of both atomic planes are driven to parallel alignment by an external magnetic field. The resistance change associated with the transition from antiparallel to parallel configuration is qualitatively similar to that observed in artificially layered metallic magnetic structures. Detailed electronic structure of VSe2 was obtained from DFT calculations. Then, the ballistic spin-valve magnetoresistance was determined within the Landauer formalism. In addition, we also analyze thermal and thermoelectric properties. Both phases of VSe2, denoted as H and T, are considered.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Vanadium based dichalcogenides, VSe2, are two-dimensional materials in which magnetic Vanadium atoms are arranged in a hexagonal lattice and are coupled ferromagnetically within the plane. However, adjacent atomic planes are coupled antiferromagnetically. This provides new and interesting opportunities for application in spintronics and data storage and processing technologies. A spin valve magnetoresistance may be achieved when magnetic moments of both atomic planes are driven to parallel alignment by an external magnetic field. The resistance change associated with the transition from antiparallel to parallel configuration is qualitatively similar to that observed in artificially layered metallic magnetic structures. Detailed electronic structure of VSe2 was obtained from DFT calculations. Then, the ballistic spin-valve magnetoresistance was determined within the Landauer formalism. In addition, we also analyze thermal and thermoelectric properties. Both phases of VSe2, denoted as H and T, are considered. |
| 70. | Andriy E. Serebryannikov, Akhlesh Lakhtakia, Guy A E Vandenbosch, Ekmel Ozbay Scientific Reports, 12 (1), pp. 3518, 2022, ISSN: 2045-2322. @article{Serebryannikov2022, title = {Transmissive terahertz metasurfaces with vanadium dioxide split-rings and grids for switchable asymmetric polarization manipulation}, author = {Andriy E. Serebryannikov and Akhlesh Lakhtakia and Guy A E Vandenbosch and Ekmel Ozbay}, url = {https://doi.org/10.1038/s41598-022-07265-6}, doi = {10.1038/s41598-022-07265-6}, issn = {2045-2322}, year = {2022}, date = {2022-03-03}, journal = {Scientific Reports}, volume = {12}, number = {1}, pages = {3518}, abstract = {Metasurfaces containing arrays of thermally tunable metal-free (double-)split-ring meta-atoms and metal-free grids made of vanadium dioxide (VO$$_2$$), a phase-change material can deliver switching between (1) polarization manipulation in transmission mode as well as related asymmetric transmission and (2) other functionalities in the terahertz regime, especially when operation in the transmission mode is needed to be conserved for both phases of VO$$_2$$. As the meta-atom arrays function as arrays of metallic subwavelength resonators for the metallic phase of VO$$_2$$, but as transmissive phase screens for the insulator phase of VO$$_2$$, numerical simulations of double- and triple-array metasurfaces strongly indicate extreme scenarios of functionality switching also when the resulting structure comprises only VO$$_2$$ meta-atoms and VO$$_2$$ grids. More switching scenarios are achievable when only one meta-atom array or one grid is made of VO$$_2$$ components. They are enabled by the efficient coupling of the geometrically identical resonator arrays/grids that are made of the materials that strongly differ in terms of conductivity, i.e. Cu and VO$$_2$$ in the metallic phase.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Metasurfaces containing arrays of thermally tunable metal-free (double-)split-ring meta-atoms and metal-free grids made of vanadium dioxide (VO$$_2$$), a phase-change material can deliver switching between (1) polarization manipulation in transmission mode as well as related asymmetric transmission and (2) other functionalities in the terahertz regime, especially when operation in the transmission mode is needed to be conserved for both phases of VO$$_2$$. As the meta-atom arrays function as arrays of metallic subwavelength resonators for the metallic phase of VO$$_2$$, but as transmissive phase screens for the insulator phase of VO$$_2$$, numerical simulations of double- and triple-array metasurfaces strongly indicate extreme scenarios of functionality switching also when the resulting structure comprises only VO$$_2$$ meta-atoms and VO$$_2$$ grids. More switching scenarios are achievable when only one meta-atom array or one grid is made of VO$$_2$$ components. They are enabled by the efficient coupling of the geometrically identical resonator arrays/grids that are made of the materials that strongly differ in terms of conductivity, i.e. Cu and VO$$_2$$ in the metallic phase. |
| 69. | Dominika Kuźma, Łukasz Laskowski, Jarosław W. Kłos, Piotr Zieliński Effects of shape on magnetization switching in systems of magnetic elongated nanoparticles J. Magn. Magn. Mat., 545 , pp. 168685, 2022, ISSN: 0304-8853. @article{KUZMA2022168685, title = {Effects of shape on magnetization switching in systems of magnetic elongated nanoparticles}, author = {Dominika Kuźma and Łukasz Laskowski and Jarosław W. Kłos and Piotr Zieliński}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009215}, doi = {https://doi.org/10.1016/j.jmmm.2021.168685}, issn = {0304-8853}, year = {2022}, date = {2022-03-01}, journal = {J. Magn. Magn. Mat.}, volume = {545}, pages = {168685}, abstract = {The equilibrium magnetization of flat elongated magnetic nanoparticles of different shapes has been determined for a range of the static magnetic fields applied parallel to their long/easy axes. The behaviour of single particles has been compared with that of equidistant chains composed of the same particles. The shapes sharpened at the ends, i.e. elongated diamonds and two-sided swords, switch with minimal inhomogeneities of magnetization and with well rectangular hystereses. This may be useful in designing of binary memory devices. The narrowest hysteresis has been found for hourglass shapes, where the switching is preceded with inhomogeneities of magnetization so the hystereses are rounded. The shapes endowed with broadened heads, such as dumbbells and bones, show vortex-like inhomogeneities, marked with an interesting interplay of helicities, which result in a multi-stage switching with relatively large coercive fields.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The equilibrium magnetization of flat elongated magnetic nanoparticles of different shapes has been determined for a range of the static magnetic fields applied parallel to their long/easy axes. The behaviour of single particles has been compared with that of equidistant chains composed of the same particles. The shapes sharpened at the ends, i.e. elongated diamonds and two-sided swords, switch with minimal inhomogeneities of magnetization and with well rectangular hystereses. This may be useful in designing of binary memory devices. The narrowest hysteresis has been found for hourglass shapes, where the switching is preceded with inhomogeneities of magnetization so the hystereses are rounded. The shapes endowed with broadened heads, such as dumbbells and bones, show vortex-like inhomogeneities, marked with an interesting interplay of helicities, which result in a multi-stage switching with relatively large coercive fields. |
| 68. | Kacper Wrześniewski Journal of Magnetism and Magnetic Materials, 545 , pp. 168703, 2022. @article{Wrześniewski2022b, title = {Interplay of dark states and superconducting correlations in charge transport through quantum dot trimers}, author = {Kacper Wrześniewski}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009331}, doi = {10.1016/j.jmmm.2021.168703}, year = {2022}, date = {2022-03-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {545}, pages = {168703}, abstract = {Electronic transport through a hybrid triple quantum dot system is theoretically studied by means of the real-time diagrammatic technique in the lowest order of perturbation theory. The central part of the system is arranged in a triangular geometry, with two quantum dots weakly coupled to metallic electrodes, while the third dot is proximitized by an s-wave superconductor. The focus is put on the transport regimes, where one- and two-electron dark states are formed due to the destructive interference of the electronic wavefunctions. This effect greatly influences the properties of the system, leading to the coherent population trapping and consequently to current blockade, negative differential conductance and enhanced shot-noise. It is shown that the presence of the superconducting pairing correlations in the system can lift the dark state blockade and reduce the shot-noise. Moreover, the current oscillations due to the magnetic flux enclosed by the triangular structure and the effect of superconducting correlations are considered. When the dark state has eigenenergy near the chemical potential of superconducting electrode, the amplitude of oscillations is strongly reduced while the current blockade is lifted. However, when the eigenenergy of the dark state is shifted away from the chemical potential of superconducting lead, the current oscillations remain unaffected.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Electronic transport through a hybrid triple quantum dot system is theoretically studied by means of the real-time diagrammatic technique in the lowest order of perturbation theory. The central part of the system is arranged in a triangular geometry, with two quantum dots weakly coupled to metallic electrodes, while the third dot is proximitized by an s-wave superconductor. The focus is put on the transport regimes, where one- and two-electron dark states are formed due to the destructive interference of the electronic wavefunctions. This effect greatly influences the properties of the system, leading to the coherent population trapping and consequently to current blockade, negative differential conductance and enhanced shot-noise. It is shown that the presence of the superconducting pairing correlations in the system can lift the dark state blockade and reduce the shot-noise. Moreover, the current oscillations due to the magnetic flux enclosed by the triangular structure and the effect of superconducting correlations are considered. When the dark state has eigenenergy near the chemical potential of superconducting electrode, the amplitude of oscillations is strongly reduced while the current blockade is lifted. However, when the eigenenergy of the dark state is shifted away from the chemical potential of superconducting lead, the current oscillations remain unaffected. |
| 67. | Kateryna Boboshko, Anna Dyrdał, Józef Barnaś Journal of Magnetism and Magnetic Materials, 545 , pp. 168698, 2022. @article{Boboshko2022, title = {Bilinear magnetoresistance in topological insulators: The role of spin–orbit scattering on impurities}, author = {Kateryna Boboshko and Anna Dyrdał and Józef Barnaś}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009318}, doi = {10.1016/j.jmmm.2021.168698}, year = {2022}, date = {2022-03-01}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {545}, pages = {168698}, abstract = {Bilinear magnetoresistance (BMR) is a new kind of magnetoresistance, that scales linearly with electric and magnetic fields. This magnetoresistance occurs in systems with strong spin–orbit interaction. Additionally, this interaction also leads to quadratic magnetoresistance (QMR). We consider theoretically BMR and QMR in surface states of 3D topological insulators, and propose a new mechanism that leads to these effects. This mechanism is based on scattering on spin–orbit impurities. Accordingly, we assume the minimal model of surface electronic states in a single independent surface of a TI, and calculate both BMR and QMR induced as an interplay of current-induced spin polarization (or equivalently effective spin–orbit field) and spin–orbit scattering on impurities. We present detailed characteristics of both BMR and QMR, and compare our results with those obtained for TIs with spin-momentum locking inhomogeneities and hexagonal warping of the Dirac cones.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Bilinear magnetoresistance (BMR) is a new kind of magnetoresistance, that scales linearly with electric and magnetic fields. This magnetoresistance occurs in systems with strong spin–orbit interaction. Additionally, this interaction also leads to quadratic magnetoresistance (QMR). We consider theoretically BMR and QMR in surface states of 3D topological insulators, and propose a new mechanism that leads to these effects. This mechanism is based on scattering on spin–orbit impurities. Accordingly, we assume the minimal model of surface electronic states in a single independent surface of a TI, and calculate both BMR and QMR induced as an interplay of current-induced spin polarization (or equivalently effective spin–orbit field) and spin–orbit scattering on impurities. We present detailed characteristics of both BMR and QMR, and compare our results with those obtained for TIs with spin-momentum locking inhomogeneities and hexagonal warping of the Dirac cones. |
| 66. | Piotr Majek, Krzysztof P. Wójcik,, Ireneusz Weymann Spin-resolved thermal signatures of Majorana-Kondo interplay in double quantum dots Phys. Rev. B, 105 , pp. 075418, 2022. @article{Majek2022b, title = {Spin-resolved thermal signatures of Majorana-Kondo interplay in double quantum dots}, author = {Piotr Majek and Krzysztof P. Wójcik, and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.105.075418}, doi = {10.1103/PhysRevB.105.075418}, year = {2022}, date = {2022-02-17}, journal = {Phys. Rev. B}, volume = {105}, pages = {075418}, abstract = {We investigate theoretically the thermoelectric transport properties of a T-shaped double quantum dot side-coupled to a topological superconducting nanowire hosting Majorana zero-energy modes. The calculations are performed using the numerical renormalization group method focusing on the transport regime, where the system exhibits the two-stage Kondo effect. It is shown that the leakage of Majorana quasiparticles into the double dot system results in a half-suppression of the second stage of the Kondo effect, which is revealed through fractional values of the charge and heat conductances and gives rise to new resonances in the Seebeck coefficient. The heat conductance is found to satisfy a modified Wiedemann-Franz law. Finally, the interplay of Majorana-induced interference with strong electron correlations is discussed in the behavior of the spin Seebeck effect, which is a unique phenomenon of the considered setup.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate theoretically the thermoelectric transport properties of a T-shaped double quantum dot side-coupled to a topological superconducting nanowire hosting Majorana zero-energy modes. The calculations are performed using the numerical renormalization group method focusing on the transport regime, where the system exhibits the two-stage Kondo effect. It is shown that the leakage of Majorana quasiparticles into the double dot system results in a half-suppression of the second stage of the Kondo effect, which is revealed through fractional values of the charge and heat conductances and gives rise to new resonances in the Seebeck coefficient. The heat conductance is found to satisfy a modified Wiedemann-Franz law. Finally, the interplay of Majorana-induced interference with strong electron correlations is discussed in the behavior of the spin Seebeck effect, which is a unique phenomenon of the considered setup. |
| 65. | V. A. Stephanovich, E. V. Kirichenko, V. K. Dugaev, Józef Barnaś Dynamic Friedel oscillations on the surface of a topological insulator Phys. Rev. B, 105 , pp. 075306, 2022. @article{Stephanovich2022, title = {Dynamic Friedel oscillations on the surface of a topological insulator}, author = {V. A. Stephanovich and E. V. Kirichenko and V. K. Dugaev and Józef Barnaś}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.105.075306}, doi = {10.1103/PhysRevB.105.075306}, year = {2022}, date = {2022-02-14}, journal = {Phys. Rev. B}, volume = {105}, pages = {075306}, abstract = {We study theoretically the dynamic Friedel oscillations of electrons at the surface of a topological insulator (TI) that are generated by the rotation of a localized impurity spin. We show that the spin-orbit interaction (SOI) in Rashba form, which is an integral part of the TI Hamiltonian, yields a highly anisotropic response to the localized spin rotation. As a result, the response to a flip of a localized spin z projection involves the reaction of all x, y, and z components of the local magnetization. Additionally, the dynamic spin moment (and thus also Friedel oscillations) emitted by the localized dynamical spin depends on the orientation in the TI plane. The resulting unusual dynamics is due to the interplay of SOI and Ruderman-Kittel-Kasuya-Yoshida interactions. This provides the basis for manipulation of the spin transport in topological insulators decorated with localized impurity spins, which may be important for technological applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study theoretically the dynamic Friedel oscillations of electrons at the surface of a topological insulator (TI) that are generated by the rotation of a localized impurity spin. We show that the spin-orbit interaction (SOI) in Rashba form, which is an integral part of the TI Hamiltonian, yields a highly anisotropic response to the localized spin rotation. As a result, the response to a flip of a localized spin z projection involves the reaction of all x, y, and z components of the local magnetization. Additionally, the dynamic spin moment (and thus also Friedel oscillations) emitted by the localized dynamical spin depends on the orientation in the TI plane. The resulting unusual dynamics is due to the interplay of SOI and Ruderman-Kittel-Kasuya-Yoshida interactions. This provides the basis for manipulation of the spin transport in topological insulators decorated with localized impurity spins, which may be important for technological applications. |
| 64. | Yuliya S Dadoenkova, Maciej Krawczyk, Igor L Lyubchanskii Opt. Mater. Express, 12 (2), pp. 717–726, 2022. @article{Dadoenkova:22, title = {Goos-Hoenchen shift at Brillouin light scattering by a magnetostatic wave in the Damon-Eshbach configuration [Invited]}, author = {Yuliya S Dadoenkova and Maciej Krawczyk and Igor L Lyubchanskii}, url = {http://opg.optica.org/ome/abstract.cfm?URI=ome-12-2-717}, doi = {10.1364/OME.447984}, year = {2022}, date = {2022-02-12}, journal = {Opt. Mater. Express}, volume = {12}, number = {2}, pages = {717--726}, publisher = {OSA}, abstract = {The lateral shift of an optical beam undergoing Brillouin light scattering by a spin wave propagating along the interface between magnetic and dielectric media (Damon-Eshbach configuration) in the total internal reflection geometry is studied theoretically. Linear and quadratic magneto-optic terms in polarization are taken into account. It is shown that the lateral shift depends on the polarization (s- or p-) state of the scattered electromagnetic wave as well as on the frequency of the spin wave.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The lateral shift of an optical beam undergoing Brillouin light scattering by a spin wave propagating along the interface between magnetic and dielectric media (Damon-Eshbach configuration) in the total internal reflection geometry is studied theoretically. Linear and quadratic magneto-optic terms in polarization are taken into account. It is shown that the lateral shift depends on the polarization (s- or p-) state of the scattered electromagnetic wave as well as on the frequency of the spin wave. |
| 63. | A V Chumak, P Kabos, M Wu, C Abert, C Adelmann, A O Adeyeye, J Akerman, F G Aliev, A Anane, A Awad, C H Back, A Barman, G E W Bauer, M Becherer, E N Beginin, V A S V Bittencourt, Y M Blanter, P Bortolotti, I Boventer, D A Bozhko, S A Bunyaev, J J Carmiggelt, R R Cheenikundil, F Ciubotaru, S Cotofana, G Csaba, O V Dobrovolskiy, C Dubs, M Elyasi, K G Fripp, H Fulara, I A Golovchanskiy, C Gonzalez-Ballestero, Piotr Graczyk, D Grundler, Paweł Gruszecki, G Gubbiotti, K Guslienko, A Haldar, S Hamdioui, R Hertel, B Hillebrands, T Hioki, A Houshang, C -M Hu, H Huebl, M Huth, E Iacocca, M B Jungfleisch, G N Kakazei, A Khitun, R Khymyn, T Kikkawa, M Kloui, O Klein, Jarosław W. Kłos, S Knauer, S Koraltan, M Kostylev, Maciej Krawczyk, I N Krivorotov, V V Kruglyak, D Lachance-Quirion, S Ladak, R Lebrun, Y Li, M Lindner, R Macedo, S Mayr, G A Melkov, Szymon Mieszczak, Y Nakamura, H T Nembach, A A Nikitin, S A Nikitov, V Novosad, J A Otalora, Y Otani, A Papp, B Pigeau, P Pirro, W Porod, F Porrati, H Qin, Bivas Rana, T Reimann, F Riente, O Romero-Isart, A Ross, A V Sadovnikov, A R Safin, E Saitoh, G Schmidt, H Schultheiss, K Schultheiss, A A Serga, S Sharma, J M Shaw, D Suess, O Surzhenko, Krzysztof Szulc, T Taniguchi, M Urbanek, K Usami, A B Ustinov, T van der Sar, S van Dijken, V I Vasyuchka, R Verba, Viola S Kusminskiy, Q Wang, M Weides, M Weiler, S Wintz, S P Wolski, X Zhang Advances in Magnetics Roadmap on Spin-Wave Computing IEEE Trans. Magn., 58 (6), pp. 1-72, 2022, ISSN: 1941-0069. @article{9706176, title = {Advances in Magnetics Roadmap on Spin-Wave Computing}, author = {A V Chumak and P Kabos and M Wu and C Abert and C Adelmann and A O Adeyeye and J Akerman and F G Aliev and A Anane and A Awad and C H Back and A Barman and G E W Bauer and M Becherer and E N Beginin and V A S V Bittencourt and Y M Blanter and P Bortolotti and I Boventer and D A Bozhko and S A Bunyaev and J J Carmiggelt and R R Cheenikundil and F Ciubotaru and S Cotofana and G Csaba and O V Dobrovolskiy and C Dubs and M Elyasi and K G Fripp and H Fulara and I A Golovchanskiy and C Gonzalez-Ballestero and Piotr Graczyk and D Grundler and Paweł Gruszecki and G Gubbiotti and K Guslienko and A Haldar and S Hamdioui and R Hertel and B Hillebrands and T Hioki and A Houshang and C -M Hu and H Huebl and M Huth and E Iacocca and M B Jungfleisch and G N Kakazei and A Khitun and R Khymyn and T Kikkawa and M Kloui and O Klein and Jarosław W. Kłos and S Knauer and S Koraltan and M Kostylev and Maciej Krawczyk and I N Krivorotov and V V Kruglyak and D Lachance-Quirion and S Ladak and R Lebrun and Y Li and M Lindner and R Macedo and S Mayr and G A Melkov and Szymon Mieszczak and Y Nakamura and H T Nembach and A A Nikitin and S A Nikitov and V Novosad and J A Otalora and Y Otani and A Papp and B Pigeau and P Pirro and W Porod and F Porrati and H Qin and Bivas Rana and T Reimann and F Riente and O Romero-Isart and A Ross and A V Sadovnikov and A R Safin and E Saitoh and G Schmidt and H Schultheiss and K Schultheiss and A A Serga and S Sharma and J M Shaw and D Suess and O Surzhenko and Krzysztof Szulc and T Taniguchi and M Urbanek and K Usami and A B Ustinov and T van der Sar and S van Dijken and V I Vasyuchka and R Verba and Viola S Kusminskiy and Q Wang and M Weides and M Weiler and S Wintz and S P Wolski and X Zhang}, doi = {10.1109/TMAG.2022.3149664}, issn = {1941-0069}, year = {2022}, date = {2022-02-07}, journal = {IEEE Trans. Magn.}, volume = {58}, number = {6}, pages = {1-72}, abstract = {Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors, which covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with the Boolean digital data, unconventional approaches, such as neuromorphic computing, and the progress toward magnon-based quantum computing. This article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of current challenges and the outlook of further development for each research direction.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors, which covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with the Boolean digital data, unconventional approaches, such as neuromorphic computing, and the progress toward magnon-based quantum computing. This article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of current challenges and the outlook of further development for each research direction. |
| 62. | Krzysztof Sobucki, Paweł Gruszecki, Justyna Rychły, Maciej Krawczyk IEEE Transactions on Magnetics, 58 (2), pp. 1-5, 2022, ISSN: 1941-0069. @article{9450803, title = {Control of the Phase of Reflected Spin Waves From Magnonic Gires–Tournois Interferometer of Subwavelength Width}, author = {Krzysztof Sobucki and Paweł Gruszecki and Justyna Rychły and Maciej Krawczyk}, doi = {10.1109/TMAG.2021.3088298}, issn = {1941-0069}, year = {2022}, date = {2022-01-20}, journal = {IEEE Transactions on Magnetics}, volume = {58}, number = {2}, pages = {1-5}, abstract = {The phase is one of the fundamental properties of a wave that allows to control interference effects and can be used to efficiently encode information. We examine numerically a magnonic resonator of the Gires–Tournois interferometer type, which enables the control of the phase of spin waves (SWs) reflected from the edge of the ferromagnetic film. The considered interferometer consists of a Py thin film and a thin, narrow Py stripe placed above its edge, both coupled magnetostatically. We show that the resonances and the phase of the reflected SWs are sensitive for a variation of the geometrical parameters of this bi-layered part of the system. The high sensitivity to film, stripe, and non-magnetic spacer thicknesses offers a prospect for developing magnonic metasurfaces and sensors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The phase is one of the fundamental properties of a wave that allows to control interference effects and can be used to efficiently encode information. We examine numerically a magnonic resonator of the Gires–Tournois interferometer type, which enables the control of the phase of spin waves (SWs) reflected from the edge of the ferromagnetic film. The considered interferometer consists of a Py thin film and a thin, narrow Py stripe placed above its edge, both coupled magnetostatically. We show that the resonances and the phase of the reflected SWs are sensitive for a variation of the geometrical parameters of this bi-layered part of the system. The high sensitivity to film, stripe, and non-magnetic spacer thicknesses offers a prospect for developing magnonic metasurfaces and sensors. |
| 61. | Damian Tomaszewski, Piotr Busz, Jan Martinek Kondo effect in the presence of the spin accumulation and non-equilibrium spin currents Journal of Magnetism and Magnetic Materials, 542 , pp. 168592, 2022. @article{Tomaszewski2022, title = {Kondo effect in the presence of the spin accumulation and non-equilibrium spin currents}, author = {Damian Tomaszewski and Piotr Busz and Jan Martinek}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321008362}, doi = {10.1016/j.jmmm.2021.168592}, year = {2022}, date = {2022-01-15}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {542}, pages = {168592}, abstract = {We present a theoretical description of the spin accumulation effect in metallic Fermi leads on the Kondo effect in the quantum dot attached to those. It has been shown that the spin accumulation by breaking the spin symmetry leads to the suppression of the Kondo effect in some cases. In order to better understand the observed effects, we analyze the spin currents in the system, depending on the spin accumulation of the electrodes, for both symmetrical and anti-symmetrical configuration of spin accumulation. We demonstrate that in the absence of the Kondo resonance splitting the suppression of the Kondo effect is related to the presence of the non-equilibrium spin current in the system.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present a theoretical description of the spin accumulation effect in metallic Fermi leads on the Kondo effect in the quantum dot attached to those. It has been shown that the spin accumulation by breaking the spin symmetry leads to the suppression of the Kondo effect in some cases. In order to better understand the observed effects, we analyze the spin currents in the system, depending on the spin accumulation of the electrodes, for both symmetrical and anti-symmetrical configuration of spin accumulation. We demonstrate that in the absence of the Kondo resonance splitting the suppression of the Kondo effect is related to the presence of the non-equilibrium spin current in the system. |
| 60. | Aleksandra Trzaskowska, P Graczyk, Nandan K. P. Babu, Miłosz Zdunek, H Głowiński, Jarosław W. Kłos, Sławomir Mielcarek The studies on phonons and magnons in [CoFeB/Au]N multilayers of different number of repetitions Journal of Magnetism and Magnetic Materials, 549 , pp. 169049, 2022, ISSN: 0304-8853. @article{TRZASKOWSKA2022169049, title = {The studies on phonons and magnons in [CoFeB/Au]N multilayers of different number of repetitions}, author = {Aleksandra Trzaskowska and P Graczyk and Nandan K. P. Babu and Miłosz Zdunek and H Głowiński and Jarosław W. Kłos and Sławomir Mielcarek}, url = {https://www.sciencedirect.com/science/article/pii/S0304885322000300}, doi = {https://doi.org/10.1016/j.jmmm.2022.169049}, issn = {0304-8853}, year = {2022}, date = {2022-01-13}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {549}, pages = {169049}, abstract = {We investigated the interaction between spin waves and surface acoustic waves in the [CoFeB/Au]N multilayer deposited on the silicon substrate by Brillion light scattering spectroscopy. We showed that this kind of coupling manifested as an anticrossing in magnetoelastic dispersion relation, can be modified by changing the number of repetitions within the multilayer. The observed modification is attributed mostly to the change in the strength of dipolar interactions which alter the dispersion branch of spin wave fundamental mode and shifts the anticrossing towards larger wave vectors where the magnetoelastic coupling is stronger. The studied range of the wave vector was varied between 0.6·105 cm−1 and 2.2·105 cm−1 while the frequency range of investigations was between 3 and 20 GHz.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigated the interaction between spin waves and surface acoustic waves in the [CoFeB/Au]N multilayer deposited on the silicon substrate by Brillion light scattering spectroscopy. We showed that this kind of coupling manifested as an anticrossing in magnetoelastic dispersion relation, can be modified by changing the number of repetitions within the multilayer. The observed modification is attributed mostly to the change in the strength of dipolar interactions which alter the dispersion branch of spin wave fundamental mode and shifts the anticrossing towards larger wave vectors where the magnetoelastic coupling is stronger. The studied range of the wave vector was varied between 0.6·105 cm−1 and 2.2·105 cm−1 while the frequency range of investigations was between 3 and 20 GHz. |
| 59. | Anna Krzyżewska, Anna Dyrdał Physica E, 135 , pp. 114961, 2022, ISSN: 1386-9477. @article{physicaE_2021.114961, title = {Non-equilibrium spin polarization in magnetic two-dimensional electron gas with k-linear and k-cubed Dresselhaus spin–orbit interaction}, author = {Anna Krzyżewska and Anna Dyrdał}, url = {https://doi.org/10.1016/j.physe.2021.114961}, doi = {10.1016/j.physe.2021.114961}, issn = {1386-9477}, year = {2022}, date = {2022-01-01}, journal = {Physica E}, volume = {135}, pages = {114961}, publisher = {North-Holland}, abstract = {The current-induced spin polarization (CISP) of charge carriers is one of the main mechanisms of spin-to-charge interconversion effects that can be used in new spintronics devices. Here, CISP is studied theoreticallyin symmetric quantum wells growing in [001] crystallographic direction, where both𝑘-linear and𝑘-cubedDresselhaus spin–orbit interactions are present. The exchange interaction responsible for perpendicular to planenet magnetization is also taken into account. The main focus is on the influence of cubic Dresselhaus termon CISP and the interplay between spin–orbit interaction (SOI) and the exchange field. The analytical andnumerical results are derived within the linear response theory and Matsubara Green’s function formalism.Apart from detailed numerical results, we also provide some analytical expressions that may be usefulfor interpretation of experimental results and for characterization of quantum wells with Dresselhaus SOI.Analytical expressions for the relevant Berry curvature are also derived, and it is shown that the Berrycurvature in magnetic 2DEG with cubic Dresselhaus interaction oscillates in the𝑘-space, while its averagedvalue is reduced. We also analyze the temperature behavior of CISP and calculate the low-temperature spinpolarizability due to heat current.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The current-induced spin polarization (CISP) of charge carriers is one of the main mechanisms of spin-to-charge interconversion effects that can be used in new spintronics devices. Here, CISP is studied theoreticallyin symmetric quantum wells growing in [001] crystallographic direction, where both𝑘-linear and𝑘-cubedDresselhaus spin–orbit interactions are present. The exchange interaction responsible for perpendicular to planenet magnetization is also taken into account. The main focus is on the influence of cubic Dresselhaus termon CISP and the interplay between spin–orbit interaction (SOI) and the exchange field. The analytical andnumerical results are derived within the linear response theory and Matsubara Green’s function formalism.Apart from detailed numerical results, we also provide some analytical expressions that may be usefulfor interpretation of experimental results and for characterization of quantum wells with Dresselhaus SOI.Analytical expressions for the relevant Berry curvature are also derived, and it is shown that the Berrycurvature in magnetic 2DEG with cubic Dresselhaus interaction oscillates in the𝑘-space, while its averagedvalue is reduced. We also analyze the temperature behavior of CISP and calculate the low-temperature spinpolarizability due to heat current. |
| 58. | Maciej Lewenstein, David Cirauqui, Miguel Angel Garcia-March, Guillem Guigo i Corominas, Przemyslaw R Grzybowski, Jose Saavedra, Martin Wilkens, Jan Wehr Haake-Lewenstein-Wilkens approach to spin-glasses revisited Journal of Physics A: Mathematical and Theoretical, 2022. @article{10.1088/1751-8121/ac9d10, title = {Haake-Lewenstein-Wilkens approach to spin-glasses revisited}, author = {Maciej Lewenstein and David Cirauqui and Miguel Angel Garcia-March and Guillem Guigo i Corominas and Przemyslaw R Grzybowski and Jose Saavedra and Martin Wilkens and Jan Wehr}, url = {http://iopscience.iop.org/article/10.1088/1751-8121/ac9d10}, year = {2022}, date = {2022-01-01}, journal = {Journal of Physics A: Mathematical and Theoretical}, abstract = {We revisit the Haake-Lewenstein-Wilkens (HLW) approach to Edwards-Anderson (EA) model of Ising spin glass [Phys. Rev. Lett. 55, 2606 (1985)]. This approach consists in evaluation and analysis of the probability distribution of configurations of two replicas of the system, averaged over quenched disorder. This probability This approximate result suggest that qEA > 0 at 0 < T < Tc in 3D and 4D. The case of 2D seems to be a little more subtle, since in the present approach energy increase for a domain wall competes with boundary/edge effects more strongly in 2D; still our approach predicts spin glass order at sufficiently low temperature. We speculate, how these predictions confirm/contradict widely spread opinions that: i) There exist only one (up to the spin flip) ground state in EA model in 2D, 3D and 4D; ii) There is (no) spin glass transition in 3D and 4D (2D). This paper is dedicated to the memories of Fritz Haake and Marek Cieplak.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We revisit the Haake-Lewenstein-Wilkens (HLW) approach to Edwards-Anderson (EA) model of Ising spin glass [Phys. Rev. Lett. 55, 2606 (1985)]. This approach consists in evaluation and analysis of the probability distribution of configurations of two replicas of the system, averaged over quenched disorder. This probability This approximate result suggest that qEA > 0 at 0 < T < Tc in 3D and 4D. The case of 2D seems to be a little more subtle, since in the present approach energy increase for a domain wall competes with boundary/edge effects more strongly in 2D; still our approach predicts spin glass order at sufficiently low temperature. We speculate, how these predictions confirm/contradict widely spread opinions that: i) There exist only one (up to the spin flip) ground state in EA model in 2D, 3D and 4D; ii) There is (no) spin glass transition in 3D and 4D (2D). This paper is dedicated to the memories of Fritz Haake and Marek Cieplak. |
2021 |
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| 57. | Fabrizio Minganti, Ievgen I Arkhipov, Adam Miranowicz, Franco Nori Continuous dissipative phase transitions with or without symmetry breaking New Journal of Physics, 23 (12), pp. 122001, 2021. @article{Minganti2021b, title = {Continuous dissipative phase transitions with or without symmetry breaking}, author = {Fabrizio Minganti and Ievgen I Arkhipov and Adam Miranowicz and Franco Nori}, url = {https://doi.org/10.1088/1367-2630/ac3db8}, doi = {10.1088/1367-2630/ac3db8}, year = {2021}, date = {2021-12-22}, journal = {New Journal of Physics}, volume = {23}, number = {12}, pages = {122001}, publisher = {IOP Publishing}, abstract = {The paradigm of second-order phase transitions (PTs) induced by spontaneous symmetry breaking (SSB) in thermal and quantum systems is a pillar of modern physics that has been fruitfully applied to out-of-equilibrium open quantum systems. Dissipative phase transitions (DPTs) of second order are often connected with SSB, in close analogy with well-known thermal second-order PTs in closed quantum and classical systems. That is, a second-order DPT should disappear by preventing the occurrence of SSB. Here, we prove this statement to be wrong, showing that, surprisingly, SSB is not a necessary condition for the occurrence of second-order DPTs in out-of-equilibrium open quantum systems. We analytically prove this result using the Liouvillian theory of DPTs, and demonstrate this anomalous transition in a paradigmatic laser model, where we can arbitrarily remove SSB while retaining criticality, and on a Z2-symmetric model of a two-photon Kerr resonator. This new type of PT cannot be interpreted as a ‘semiclassical’ bifurcation, because, after the DPT, the system steady state remains unique.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The paradigm of second-order phase transitions (PTs) induced by spontaneous symmetry breaking (SSB) in thermal and quantum systems is a pillar of modern physics that has been fruitfully applied to out-of-equilibrium open quantum systems. Dissipative phase transitions (DPTs) of second order are often connected with SSB, in close analogy with well-known thermal second-order PTs in closed quantum and classical systems. That is, a second-order DPT should disappear by preventing the occurrence of SSB. Here, we prove this statement to be wrong, showing that, surprisingly, SSB is not a necessary condition for the occurrence of second-order DPTs in out-of-equilibrium open quantum systems. We analytically prove this result using the Liouvillian theory of DPTs, and demonstrate this anomalous transition in a paradigmatic laser model, where we can arbitrarily remove SSB while retaining criticality, and on a Z2-symmetric model of a two-photon Kerr resonator. This new type of PT cannot be interpreted as a ‘semiclassical’ bifurcation, because, after the DPT, the system steady state remains unique. |
| 56. | Kateřina Jirákov á, Antonín Č, Karel Lemr, Karol Bartkiewicz, Adam Miranowicz Physical Review A, 104 (6), pp. 062436, 2021. @article{Jirakova2021b, title = {Experimental hierarchy and optimal robustness of quantum correlations of two-qubit states with controllable white noise}, author = {Kate{ř}ina Jirákov á and Antonín Č and Karel Lemr and Karol Bartkiewicz and Adam Miranowicz}, url = {https://doi.org/10.1103/physreva.104.062436}, doi = {10.1103/physreva.104.062436}, year = {2021}, date = {2021-12-21}, journal = {Physical Review A}, volume = {104}, number = {6}, pages = {062436}, publisher = {American Physical Society (APS)}, abstract = {We demonstrate a hierarchy of various classes of quantum correlations on experimentally prepared two-qubit Werner-like states with controllable white noise. Werner states, which are white-noise-affected Bell states, are prototypal examples for studying such a hierarchy as a function of the amount of white noise. We experimentally generate Werner states and their generalizations, i.e., partially entangled pure states affected by white noise. These states enable us to study the hierarchy of the following classes of correlations: separability, entanglement, steering in three- and two-measurement scenarios, and Bell nonlocality. We show that the generalized Werner states (GWSs) reveal fundamentally different aspects of the hierarchy compared to the Werner states. In particular, we find five different parameter regimes of the GWSs, including those steerable in a two-measurement scenario but not violating Bell inequalities. This regime cannot be observed for the usual Werner states. Moreover, we find threshold curves separating different regimes of the quantum correlations and find the optimal states which allow for the largest amount of white noise which does not destroy their specific quantum correlations (e.g., unsteerable entanglement). Thus, we could identify the optimal Bell-nondiagonal GWSs which are, for this specific meaning, more robust against the white noise compared to the Bell-diagonal GWSs (i.e., Werner states).}, keywords = {}, pubstate = {published}, tppubtype = {article} } We demonstrate a hierarchy of various classes of quantum correlations on experimentally prepared two-qubit Werner-like states with controllable white noise. Werner states, which are white-noise-affected Bell states, are prototypal examples for studying such a hierarchy as a function of the amount of white noise. We experimentally generate Werner states and their generalizations, i.e., partially entangled pure states affected by white noise. These states enable us to study the hierarchy of the following classes of correlations: separability, entanglement, steering in three- and two-measurement scenarios, and Bell nonlocality. We show that the generalized Werner states (GWSs) reveal fundamentally different aspects of the hierarchy compared to the Werner states. In particular, we find five different parameter regimes of the GWSs, including those steerable in a two-measurement scenario but not violating Bell inequalities. This regime cannot be observed for the usual Werner states. Moreover, we find threshold curves separating different regimes of the quantum correlations and find the optimal states which allow for the largest amount of white noise which does not destroy their specific quantum correlations (e.g., unsteerable entanglement). Thus, we could identify the optimal Bell-nondiagonal GWSs which are, for this specific meaning, more robust against the white noise compared to the Bell-diagonal GWSs (i.e., Werner states). |
| 55. | Fabrizio Minganti, Ievgen I Arkhipov, Adam Miranowicz, Franco Nori Liouvillian spectral collapse in the Scully-Lamb laser model Physical Review Research, 3 (4), pp. 043197, 2021. @article{Minganti2021, title = {Liouvillian spectral collapse in the Scully-Lamb laser model}, author = {Fabrizio Minganti and Ievgen I Arkhipov and Adam Miranowicz and Franco Nori}, url = {https://doi.org/10.1103/physrevresearch.3.043197}, doi = {10.1103/physrevresearch.3.043197}, year = {2021}, date = {2021-12-21}, journal = {Physical Review Research}, volume = {3}, number = {4}, pages = {043197}, publisher = {American Physical Society (APS)}, abstract = {Phase transitions of thermal systems and the laser threshold were first connected more than forty years ago. Despite the nonequilibrium nature of the laser, the Landau theory of thermal phase transitions, applied directly to the Scully-Lamb laser model (SLLM), indicates that the laser threshold is a second-order phase transition, associated with a U(1) spontaneous symmetry breaking (SSB). To capture the genuine nonequilibrium phase transition of the SLLM (i.e., a single-mode laser without a saturable absorber), here we employ a quantum theory of dissipative phase transitions. Our results confirm that the U(1) SSB can occur at the lasing threshold but, in contrast to the Landau theory and semiclassical approximation, they signal that the SLLM “fundamental” transition is a different phenomenon, which we call Liouvillian spectral collapse; that is, the emergence of diabolic points of infinite degeneracy. By considering a generalized SLLM with additional dephasing, we witness a second-order phase transition, with a Liouvillian spectral collapse, but in the absence of symmetry breaking. Most surprisingly, the phase transition corresponds to the emergence of dynamical multistability even without SSB. Normally, bistability is suppressed by quantum fluctuations, while in this case, the very presence of quantum fluctuations enables bistability. This rather anomalous bistability, characterizing the truly dissipative and quantum origin of lasing, can be an experimental signature of our predictions, and we show that it is associated with an emergent dynamical hysteresis.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Phase transitions of thermal systems and the laser threshold were first connected more than forty years ago. Despite the nonequilibrium nature of the laser, the Landau theory of thermal phase transitions, applied directly to the Scully-Lamb laser model (SLLM), indicates that the laser threshold is a second-order phase transition, associated with a U(1) spontaneous symmetry breaking (SSB). To capture the genuine nonequilibrium phase transition of the SLLM (i.e., a single-mode laser without a saturable absorber), here we employ a quantum theory of dissipative phase transitions. Our results confirm that the U(1) SSB can occur at the lasing threshold but, in contrast to the Landau theory and semiclassical approximation, they signal that the SLLM “fundamental” transition is a different phenomenon, which we call Liouvillian spectral collapse; that is, the emergence of diabolic points of infinite degeneracy. By considering a generalized SLLM with additional dephasing, we witness a second-order phase transition, with a Liouvillian spectral collapse, but in the absence of symmetry breaking. Most surprisingly, the phase transition corresponds to the emergence of dynamical multistability even without SSB. Normally, bistability is suppressed by quantum fluctuations, while in this case, the very presence of quantum fluctuations enables bistability. This rather anomalous bistability, characterizing the truly dissipative and quantum origin of lasing, can be an experimental signature of our predictions, and we show that it is associated with an emergent dynamical hysteresis. |
| 54. | Monika Aidelsburger, Luca Barbiero, Alejandro Bermudez, Titas Chanda, Alexandre Dauphin, Daniel González-Cuadra, Przemysław R. Grzybowski, Simon Hands, Fred Jendrzejewski, Johannes Jünemann adn Gediminas Juzeliu ̄nas, Valentin Kasper, Angelo Piga, Shi-Ju Ran, Matteo Rizzi, Germán Sierra, Luca Tagliacozzo, Emanuele Tirrito, Torsten V. Zache, Jakub Zakrzewski, Erez Zohar, Maciej Lewenstein Cold atoms meet lattice gauge theory Philos. Trans. A Math. Phys. Eng. Sci., 380 (2216), pp. 20210064, 2021. @article{Aidelsburger2022-be, title = {Cold atoms meet lattice gauge theory}, author = {Monika Aidelsburger and Luca Barbiero and Alejandro Bermudez and Titas Chanda and Alexandre Dauphin and Daniel González-Cuadra and Przemysław R. Grzybowski and Simon Hands and Fred Jendrzejewski and Johannes Jünemann adn Gediminas Juzeliu ̄nas and Valentin Kasper and Angelo Piga and Shi-Ju Ran and Matteo Rizzi and Germán Sierra and Luca Tagliacozzo and Emanuele Tirrito and Torsten V. Zache and Jakub Zakrzewski and Erez Zohar and Maciej Lewenstein}, url = {https://royalsocietypublishing.org/doi/10.1098/rsta.2021.0064}, doi = {10.1098/rsta.2021.0064}, year = {2021}, date = {2021-12-20}, journal = {Philos. Trans. A Math. Phys. Eng. Sci.}, volume = {380}, number = {2216}, pages = {20210064}, publisher = {The Royal Society}, abstract = {The central idea of this review is to consider quantum field theory models relevant for particle physics and replace the fermionic matter in these models by a bosonic one. This is mostly motivated by the fact that bosons are more áccessible' and easier to manipulate for experimentalists, but this 'substitution' also leads to new physics and novel phenomena. It allows us to gain new information about among other things confinement and the dynamics of the deconfinement transition. We will thus consider bosons in dynamical lattices corresponding to the bosonic Schwinger or [Formula: see text] Bose-Hubbard models. Another central idea of this review concerns atomic simulators of paradigmatic models of particle physics theory such as the Creutz-Hubbard ladder, or Gross-Neveu-Wilson and Wilson-Hubbard models. This article is not a general review of the rapidly growing field-it reviews activities related to quantum simulations for lattice field theories performed by the Quantum Optics Theory group at ICFO and their collaborators from 19 institutions all over the world. Finally, we will briefly describe our efforts to design experimentally friendly simulators of these and other models relevant for particle physics. This article is part of the theme issue 'Quantum technologies in particle physics'.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The central idea of this review is to consider quantum field theory models relevant for particle physics and replace the fermionic matter in these models by a bosonic one. This is mostly motivated by the fact that bosons are more áccessible' and easier to manipulate for experimentalists, but this 'substitution' also leads to new physics and novel phenomena. It allows us to gain new information about among other things confinement and the dynamics of the deconfinement transition. We will thus consider bosons in dynamical lattices corresponding to the bosonic Schwinger or [Formula: see text] Bose-Hubbard models. Another central idea of this review concerns atomic simulators of paradigmatic models of particle physics theory such as the Creutz-Hubbard ladder, or Gross-Neveu-Wilson and Wilson-Hubbard models. This article is not a general review of the rapidly growing field-it reviews activities related to quantum simulations for lattice field theories performed by the Quantum Optics Theory group at ICFO and their collaborators from 19 institutions all over the world. Finally, we will briefly describe our efforts to design experimentally friendly simulators of these and other models relevant for particle physics. This article is part of the theme issue 'Quantum technologies in particle physics'. |
| 53. | Andrzej Grudka, Paweł Kurzyński, Antoni Wójcik Quantum semipermeable barriers: Investigating Maxwell's demon toolbox Physical Review E, 104 , pp. 064114, 2021. @article{Grudka2021, title = {Quantum semipermeable barriers: Investigating Maxwell's demon toolbox}, author = {Andrzej Grudka and Paweł Kurzyński and Antoni Wójcik}, url = {https://journals.aps.org/pre/abstract/10.1103/PhysRevE.104.064114}, doi = {10.1103/PhysRevE.104.064114}, year = {2021}, date = {2021-12-10}, journal = {Physical Review E}, volume = {104}, pages = {064114}, abstract = {We study quantum Maxwell's demon in a discrete space-time setup. We consider a collection of particles hopping on a one-dimensional chain and a semipermeable barrier that allows the particles to hop in only one direction. Our main result is a formulation of a local unitary dynamics describing the action of this barrier. Such dynamics utilizes an auxiliary system A and we study how properties of A influence the behavior of particles. An immediate consequence of unitarity is the fact that particles cannot be trapped on one side of the barrier forever, unless A is infinite. In addition, coherent superpositions and quantum correlations are affected once particles enter the confinement region. Finally, we show that initial superposition of A allows the barrier to act as a beam splitter.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study quantum Maxwell's demon in a discrete space-time setup. We consider a collection of particles hopping on a one-dimensional chain and a semipermeable barrier that allows the particles to hop in only one direction. Our main result is a formulation of a local unitary dynamics describing the action of this barrier. Such dynamics utilizes an auxiliary system A and we study how properties of A influence the behavior of particles. An immediate consequence of unitarity is the fact that particles cannot be trapped on one side of the barrier forever, unless A is infinite. In addition, coherent superpositions and quantum correlations are affected once particles enter the confinement region. Finally, we show that initial superposition of A allows the barrier to act as a beam splitter. |
| 52. | Jarosław W. Kłos, Maciej Krawczyk, Szymon Mieszczak, Paweł Gruszecki 2021 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS), pp. 518-521, 2021. @inproceedings{9629033, title = {The interplay between spin waves and microwave magnetic field in magnetization textures and planar magnetic nanostructures}, author = {Jarosław W. Kłos and Maciej Krawczyk and Szymon Mieszczak and Paweł Gruszecki}, doi = {10.1109/COMCAS52219.2021.9629033}, year = {2021}, date = {2021-12-06}, booktitle = {2021 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS)}, pages = {518-521}, abstract = {The magnetic microwave field is accompanying the magnetization precession in magnetic materials. However, the precessional dynamics can propagate in the form of the dipolar spin wave only if the magnetic field can effectively mediate the coupling between the magnetic moments at the distance. We refer to counter-intuitive but well known effect - the absence of the dynamic dipolar coupling in an unconstrained and uniformly magnetized medium, to stress the role of the confined geometries and magnetization textures for shaping the dipolar interaction and molding the propagation of the dipolar spin waves. The paper discusses the electromagnetic origin of the dipolar spin waves and explains the role of magnetostatic approximation. Within this approximation, we can introduce the concept of magnetostatic potential, which is very useful for describing of the origin of the dynamic demagnetizing field providing the coupling for the dipolar spin waves.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } The magnetic microwave field is accompanying the magnetization precession in magnetic materials. However, the precessional dynamics can propagate in the form of the dipolar spin wave only if the magnetic field can effectively mediate the coupling between the magnetic moments at the distance. We refer to counter-intuitive but well known effect - the absence of the dynamic dipolar coupling in an unconstrained and uniformly magnetized medium, to stress the role of the confined geometries and magnetization textures for shaping the dipolar interaction and molding the propagation of the dipolar spin waves. The paper discusses the electromagnetic origin of the dipolar spin waves and explains the role of magnetostatic approximation. Within this approximation, we can introduce the concept of magnetostatic potential, which is very useful for describing of the origin of the dynamic demagnetizing field providing the coupling for the dipolar spin waves. |
| 51. | Michał Inglot, Vitalii K. Dugaev, Anna Dyrdał, Józef Barnaś Phys. Rev. B, 104 (21), pp. 214408, 2021, ISSN: 2469-9969. @article{Inglot2021, title = {Graphene with Rashba spin-orbit interaction and coupling to a magnetic layer: Electron states localized at the domain wall}, author = {Michał Inglot and Vitalii K. Dugaev and Anna Dyrdał and Józef Barnaś}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.104.214408}, doi = {10.1103/PhysRevB.104.214408}, issn = {2469-9969}, year = {2021}, date = {2021-12-06}, journal = {Phys. Rev. B}, volume = {104}, number = {21}, pages = {214408}, abstract = {Electron states localized at a magnetic domain wall in a graphene with Rashba spin-orbit interaction and coupled to a magnetic layer are studied theoretically. It is shown that two one-dimensional bands of edge modes propagating along the domain wall emerge in the energy gap for each Dirac point, and the modes associated with different Dirac points K and K′ are the same. The coefficients describing decay of the corresponding wave functions with distance from the domain wall contain generally real and imaginary terms. Numerical results on the local spin density and on the total spin expected in the edge states characterized by the wave number ky are presented and discussed. The Chern number for a single magnetic domain on graphene indicates that the system is in the quantum anomalous Hall phase, with two chiral modes at the edges. In turn, the number of modes localized at the domain wall is determined by the difference in Chern numbers on both sides of the wall. These numbers are equal to 2 and −2, respectively, so there are four modes localized at the domain wall.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Electron states localized at a magnetic domain wall in a graphene with Rashba spin-orbit interaction and coupled to a magnetic layer are studied theoretically. It is shown that two one-dimensional bands of edge modes propagating along the domain wall emerge in the energy gap for each Dirac point, and the modes associated with different Dirac points K and K′ are the same. The coefficients describing decay of the corresponding wave functions with distance from the domain wall contain generally real and imaginary terms. Numerical results on the local spin density and on the total spin expected in the edge states characterized by the wave number ky are presented and discussed. The Chern number for a single magnetic domain on graphene indicates that the system is in the quantum anomalous Hall phase, with two chiral modes at the edges. In turn, the number of modes localized at the domain wall is determined by the difference in Chern numbers on both sides of the wall. These numbers are equal to 2 and −2, respectively, so there are four modes localized at the domain wall. |
| 50. | X. Zhou, Elena V. Tartakovskaya, G. N. Kakazei, A. O. Adeyeye Phys. Rev. B, 104 , pp. 214402, 2021. @article{PhysRevB.104.214402, title = {Engineering spin wave spectra in thick Ni80Fe20 rings by using competition between exchange and dipolar fields}, author = {X. Zhou and Elena V. Tartakovskaya and G. N. Kakazei and A. O. Adeyeye}, url = {https://link.aps.org/doi/10.1103/PhysRevB.104.214402}, doi = {10.1103/PhysRevB.104.214402}, year = {2021}, date = {2021-12-03}, journal = {Phys. Rev. B}, volume = {104}, pages = {214402}, publisher = {American Physical Society}, abstract = {Control of the spin wave dynamics in nanomagnetic elements is very important for the realization of a broad range of novel magnonic devices. Here we study experimentally the spin wave resonance in thick ferromagnetic rings (100 nm) using perpendicular ferromagnetic resonance spectroscopy. Different from what was observed for the continuous film of the same thickness, or from rings with similar lateral dimensions but with lower thicknesses, the spectra of thick patterned rings show a nonmonotonic dependence of the mode intensity on the resonance field for a fixed frequency. To explain this effect, the theoretical approach by considering the dependence of the mode profiles on both the radial and axial coordinates was developed. It was demonstrated that such unusual behavior is a result of the competition between exchange and dipolar fields acting at the spin excitations in the structure under study. The calculations are in a good agreement with the experimental results.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Control of the spin wave dynamics in nanomagnetic elements is very important for the realization of a broad range of novel magnonic devices. Here we study experimentally the spin wave resonance in thick ferromagnetic rings (100 nm) using perpendicular ferromagnetic resonance spectroscopy. Different from what was observed for the continuous film of the same thickness, or from rings with similar lateral dimensions but with lower thicknesses, the spectra of thick patterned rings show a nonmonotonic dependence of the mode intensity on the resonance field for a fixed frequency. To explain this effect, the theoretical approach by considering the dependence of the mode profiles on both the radial and axial coordinates was developed. It was demonstrated that such unusual behavior is a result of the competition between exchange and dipolar fields acting at the spin excitations in the structure under study. The calculations are in a good agreement with the experimental results. |
| 49. | Bivas Rana, Amrit Kumar Mondal, Supriyo Bandyopadhyay, Anjan Barman Applications of nanomagnets as dynamical systems - part II Nanotechnology, 33 (8), pp. 082002, 2021. @article{Rana_2021b, title = {Applications of nanomagnets as dynamical systems - part II}, author = {Bivas Rana and Amrit Kumar Mondal and Supriyo Bandyopadhyay and Anjan Barman}, url = {https://doi.org/10.1088/1361-6528/ac2f59}, doi = {10.1088/1361-6528/ac2f59}, year = {2021}, date = {2021-11-30}, journal = {Nanotechnology}, volume = {33}, number = {8}, pages = {082002}, publisher = {IOP Publishing}, abstract = {In Part I of this topical review, we discussed dynamical phenomena in nanomagnets, focusing primarily on magnetization reversal with an eye to digital applications. In this part, we address mostly wave-like phenomena in nanomagnets, with emphasis on spin waves in myriad nanomagnetic systems and methods of controlling magnetization dynamics in nanomagnet arrays which may have analog applications. We conclude with a discussion of some interesting spintronic phenomena that undergird the rich physics exhibited by nanomagnet assemblies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In Part I of this topical review, we discussed dynamical phenomena in nanomagnets, focusing primarily on magnetization reversal with an eye to digital applications. In this part, we address mostly wave-like phenomena in nanomagnets, with emphasis on spin waves in myriad nanomagnetic systems and methods of controlling magnetization dynamics in nanomagnet arrays which may have analog applications. We conclude with a discussion of some interesting spintronic phenomena that undergird the rich physics exhibited by nanomagnet assemblies. |
| 48. | D Kiphart, Y Harkavyi, K Balin, J Szade, Bogusław Mróz, P Kuświk, S Jurga, M Wiesner Scientific Reports, 11 (1), pp. 22980, 2021, ISSN: 2045-2322. @article{kiphart_investigations_2021, title = {Investigations of proximity-induced superconductivity in the topological insulator Bi2Te3 by microRaman spectroscopy}, author = {D Kiphart and Y Harkavyi and K Balin and J Szade and Bogusław Mróz and P Kuświk and S Jurga and M Wiesner}, url = {https://www.nature.com/articles/s41598-021-02475-w}, doi = {10.1038/s41598-021-02475-w}, issn = {2045-2322}, year = {2021}, date = {2021-11-26}, journal = {Scientific Reports}, volume = {11}, number = {1}, pages = {22980}, abstract = {We used the topological insulator (TI) Bi2Te3 and a high-temperature superconductor (HTSC) hybrid device for investigations of proximity-induced superconductivity (PS) in the TI. Application of the superconductor YBa2Cu3O7-δ (YBCO) enabled us to access higher temperature and energy scales for this phenomenon. The HTSC in the hybrid device exhibits emergence of a pseudogap state for T textgreater Tc that converts into a superconducting state with a reduced gap for T textless Tc. The conversion process has been reflected in Raman spectra collected from the TI. Complementary charge transport experiments revealed emergence of the proximity-induced superconducting gap in the TI and the reduced superconducting gap in the HTSC, but no signature of the pseudogap. This allowed us to conclude that Raman spectroscopy reveals formation of the pseudogap state but cannot distinguish the proximity-induced superconducting state in the TI from the superconducting state in the HTSC characterised by the reduced gap. Results of our experiments have shown that Raman spectroscopy is a complementary technique to classic charge transport experiments and is a powerful tool for investigation of the proximity-induced superconductivity in the Bi2Te3.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We used the topological insulator (TI) Bi2Te3 and a high-temperature superconductor (HTSC) hybrid device for investigations of proximity-induced superconductivity (PS) in the TI. Application of the superconductor YBa2Cu3O7-δ (YBCO) enabled us to access higher temperature and energy scales for this phenomenon. The HTSC in the hybrid device exhibits emergence of a pseudogap state for T textgreater Tc that converts into a superconducting state with a reduced gap for T textless Tc. The conversion process has been reflected in Raman spectra collected from the TI. Complementary charge transport experiments revealed emergence of the proximity-induced superconducting gap in the TI and the reduced superconducting gap in the HTSC, but no signature of the pseudogap. This allowed us to conclude that Raman spectroscopy reveals formation of the pseudogap state but cannot distinguish the proximity-induced superconducting state in the TI from the superconducting state in the HTSC characterised by the reduced gap. Results of our experiments have shown that Raman spectroscopy is a complementary technique to classic charge transport experiments and is a powerful tool for investigation of the proximity-induced superconductivity in the Bi2Te3. |
| 47. | Bivas Rana, Amrit Kumar Mondal, Supriyo Bandyopadhyay, Anjan Barman Applications of nanomagnets as dynamical systems - part I Nanotechnology, 33 (6), pp. 062007, 2021. @article{Rana_2021, title = {Applications of nanomagnets as dynamical systems - part I}, author = {Bivas Rana and Amrit Kumar Mondal and Supriyo Bandyopadhyay and Anjan Barman}, url = {https://doi.org/10.1088/1361-6528/ac2e75}, doi = {10.1088/1361-6528/ac2e75}, year = {2021}, date = {2021-11-19}, journal = {Nanotechnology}, volume = {33}, number = {6}, pages = {062007}, publisher = {IOP Publishing}, abstract = {When magnets are fashioned into nanoscale elements, they exhibit a wide variety of phenomena replete with rich physics and the lure of tantalizing applications. In this topical review, we discuss some of these phenomena, especially those that have come to light recently, and highlight their potential applications. We emphasize what drives a phenomenon, what undergirds the dynamics of the system that exhibits the phenomenon, how the dynamics can be manipulated, and what specific features can be harnessed for technological advances. For the sake of balance, we point out both advantages and shortcomings of nanomagnet based devices and systems predicated on the phenomena we discuss. Where possible, we chart out paths for future investigations that can shed new light on an intriguing phenomenon and/or facilitate both traditional and non-traditional applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } When magnets are fashioned into nanoscale elements, they exhibit a wide variety of phenomena replete with rich physics and the lure of tantalizing applications. In this topical review, we discuss some of these phenomena, especially those that have come to light recently, and highlight their potential applications. We emphasize what drives a phenomenon, what undergirds the dynamics of the system that exhibits the phenomenon, how the dynamics can be manipulated, and what specific features can be harnessed for technological advances. For the sake of balance, we point out both advantages and shortcomings of nanomagnet based devices and systems predicated on the phenomena we discuss. Where possible, we chart out paths for future investigations that can shed new light on an intriguing phenomenon and/or facilitate both traditional and non-traditional applications. |
| 46. | Zbigniew Tylczyński Frontiers of Physics, 14 (6), pp. 63301, 2021, ISSN: 2095-0462. @article{tylczynski_collection_2019, title = {A collection of 505 papers on false or unconfirmed ferroelectric properties in single crystals, ceramics and polymers}, author = {Zbigniew Tylczyński}, url = {https://journal.hep.com.cn/fop/EN/10.1007/s11467-019-0912-5}, doi = {10.1007/s11467-019-0912-5}, issn = {2095-0462}, year = {2021}, date = {2021-11-19}, journal = {Frontiers of Physics}, volume = {14}, number = {6}, pages = {63301}, abstract = {textlessptextgreaterThis collection presents 505 papers on ferroelectricity in single crystals, ceramics and polymers in which pointed or elliptical hysteresis loops would testify to their ferroelectric properties. In some papers, the authors ensure that ferroelectricity can occur even in materials that do not have a polar axis of symmetry.textless/ptextgreater}, keywords = {}, pubstate = {published}, tppubtype = {article} } textlessptextgreaterThis collection presents 505 papers on ferroelectricity in single crystals, ceramics and polymers in which pointed or elliptical hysteresis loops would testify to their ferroelectric properties. In some papers, the authors ensure that ferroelectricity can occur even in materials that do not have a polar axis of symmetry.textless/ptextgreater |
| 45. | Paweł Kurzyński Weighted Bures length uncovers quantum state sensitivity Physical Review E, 104 , pp. L052202, 2021. @article{Kurzyński2021, title = {Weighted Bures length uncovers quantum state sensitivity}, author = {Paweł Kurzyński}, url = {https://journals.aps.org/pre/abstract/10.1103/PhysRevE.104.L052202}, doi = {10.1103/PhysRevE.104.L052202}, year = {2021}, date = {2021-11-18}, journal = {Physical Review E}, volume = {104}, pages = {L052202}, abstract = {The unitarity of quantum evolutions implies that an overlap between two initial states does not change in time. This property is commonly believed to explain the apparent lack of state sensitivity in quantum theory, a feature that is prevailing in classical chaotic systems. However, classical state sensitivity is based on a distance between two trajectories in phase space which is a completely different mathematical concept than an overlap between two vectors in Hilbert space. It is possible that state sensitivity in quantum theory can be detected with the help of some special metric. Here we show that the recently introduced Weighted Bures length achieves this task. We numerically investigate a unitary cellular automaton of N interacting qubits and analyze how a single-qubit perturbation affects the evolution of WBL between the unperturbed and perturbed states. We observe a linear growth of WBL if the qubits are arranged into a cyclic graph and an exponential growth if they are arranged into a random bipartite graph.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The unitarity of quantum evolutions implies that an overlap between two initial states does not change in time. This property is commonly believed to explain the apparent lack of state sensitivity in quantum theory, a feature that is prevailing in classical chaotic systems. However, classical state sensitivity is based on a distance between two trajectories in phase space which is a completely different mathematical concept than an overlap between two vectors in Hilbert space. It is possible that state sensitivity in quantum theory can be detected with the help of some special metric. Here we show that the recently introduced Weighted Bures length achieves this task. We numerically investigate a unitary cellular automaton of N interacting qubits and analyze how a single-qubit perturbation affects the evolution of WBL between the unperturbed and perturbed states. We observe a linear growth of WBL if the qubits are arranged into a cyclic graph and an exponential growth if they are arranged into a random bipartite graph. |
| 44. | Marek Vanatka, Krzysztof Szulc, Ondrej Wojewoda, Carsten Dubs, Andrii V Chumak, Maciej Krawczyk, Oleksandr V Dobrovolskiy, Jarosław W. Kłos, Michal Urbánek Spin-Wave Dispersion Measurement by Variable-Gap Propagating Spin-Wave Spectroscopy Phys. Rev. Applied, 16 , pp. 054033, 2021. @article{PhysRevApplied.16.054033, title = {Spin-Wave Dispersion Measurement by Variable-Gap Propagating Spin-Wave Spectroscopy}, author = {Marek Vanatka and Krzysztof Szulc and Ondrej Wojewoda and Carsten Dubs and Andrii V Chumak and Maciej Krawczyk and Oleksandr V Dobrovolskiy and Jarosław W. Kłos and Michal Urbánek}, url = {https://link.aps.org/doi/10.1103/PhysRevApplied.16.054033}, doi = {10.1103/PhysRevApplied.16.054033}, year = {2021}, date = {2021-11-17}, journal = {Phys. Rev. Applied}, volume = {16}, pages = {054033}, publisher = {American Physical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 43. | Sławomir Mamica Influence of the demagnetizing field on the spin-wave softening in bicomponent magnonic crystals Journal of Magnetism and Magnetic Materials, 546 , pp. 168690, 2021, ISSN: 0304-8853. @article{MAMICA2022168690, title = {Influence of the demagnetizing field on the spin-wave softening in bicomponent magnonic crystals}, author = {Sławomir Mamica}, url = {https://www.sciencedirect.com/science/article/pii/S0304885321009264}, doi = {https://doi.org/10.1016/j.jmmm.2021.168690}, issn = {0304-8853}, year = {2021}, date = {2021-11-11}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {546}, pages = {168690}, abstract = {In bi-component magnonic crystals (MCs) demagnetizing field occurs around interfaces between a matrix and inclusions. As it is already shown this field strongly influences the spin-wave spectrum including the position and the width of band gaps and their response to the change of the external magnetic field. Here, we show its effect on the reversal of the mode order in the spectrum. The reversal of modes means that the modes which are excited mostly in the material with higher saturation magnetization have the lowest frequency than modes excited in the material with low saturation magnetization. We address this effect to the mode-dependent softening of spin waves resulting from the growing influence of the demagnetizing field while the external magnetic field lowers. The effect gives a possibility of the concentration of spin waves (i.e. the spatial distribution of their energy) in one of the constituent materials (the spin wave is excited much stronger in one material than in the other), the matrix or scattering centres, by the external magnetic field. As an example, we study planar bi-component MCs consisting of cobalt inclusions in permalloy matrix, as well as Py inclusions in Co matrix. We show that in both cases lowering external magnetic field drives down in the spectrum these modes which are excited mostly in Co. Moreover, the concentration of such modes in Co is enhanced.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In bi-component magnonic crystals (MCs) demagnetizing field occurs around interfaces between a matrix and inclusions. As it is already shown this field strongly influences the spin-wave spectrum including the position and the width of band gaps and their response to the change of the external magnetic field. Here, we show its effect on the reversal of the mode order in the spectrum. The reversal of modes means that the modes which are excited mostly in the material with higher saturation magnetization have the lowest frequency than modes excited in the material with low saturation magnetization. We address this effect to the mode-dependent softening of spin waves resulting from the growing influence of the demagnetizing field while the external magnetic field lowers. The effect gives a possibility of the concentration of spin waves (i.e. the spatial distribution of their energy) in one of the constituent materials (the spin wave is excited much stronger in one material than in the other), the matrix or scattering centres, by the external magnetic field. As an example, we study planar bi-component MCs consisting of cobalt inclusions in permalloy matrix, as well as Py inclusions in Co matrix. We show that in both cases lowering external magnetic field drives down in the spectrum these modes which are excited mostly in Co. Moreover, the concentration of such modes in Co is enhanced. |
| 42. | Hai Xu, Deng-Gao Lai, Yi-Bing Qian, Bang-Pin Hou, Adam Miranowicz, Franco Nori Optomechanical dynamics in the PT- and broken-PT-symmetric regimes Physical Review A, 104 (5), pp. 053518, 2021. @article{Xu2021, title = {Optomechanical dynamics in the PT- and broken-PT-symmetric regimes}, author = {Hai Xu and Deng-Gao Lai and Yi-Bing Qian and Bang-Pin Hou and Adam Miranowicz and Franco Nori}, url = {https://doi.org/10.1103/physreva.104.053518}, doi = {10.1103/physreva.104.053518}, year = {2021}, date = {2021-11-04}, journal = {Physical Review A}, volume = {104}, number = {5}, pages = {053518}, publisher = {American Physical Society (APS)}, abstract = {We theoretically study the dynamics of an optomechanical system, consisting of a passive optical mode and an active mechanical mode, in the PT- and broken-PT-symmetric regimes. By fully analytical treatments for the dynamics of the average displacement and particle numbers, we reveal the phase diagram under different conditions and the various regimes of both PT symmetry and stability of the system. We find that by appropriately tuning either mechanical gain or optomechanical coupling, both phase transitions of the PT symmetry and stability of the system can be flexibly controlled. As a result, the dynamical behaviors of the average displacement, photons, and phonons are radically changed in different regimes. The presented physical mechanism is general and this method can be extended to a general model of dissipative and amplified coupled systems. Our study shows that PT-symmetric optomechanical devices can serve as a powerful tool for the manipulation of mechanical motion, photons, and phonons.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We theoretically study the dynamics of an optomechanical system, consisting of a passive optical mode and an active mechanical mode, in the PT- and broken-PT-symmetric regimes. By fully analytical treatments for the dynamics of the average displacement and particle numbers, we reveal the phase diagram under different conditions and the various regimes of both PT symmetry and stability of the system. We find that by appropriately tuning either mechanical gain or optomechanical coupling, both phase transitions of the PT symmetry and stability of the system can be flexibly controlled. As a result, the dynamical behaviors of the average displacement, photons, and phonons are radically changed in different regimes. The presented physical mechanism is general and this method can be extended to a general model of dissipative and amplified coupled systems. Our study shows that PT-symmetric optomechanical devices can serve as a powerful tool for the manipulation of mechanical motion, photons, and phonons. |
| 41. | Ying Li, Ya-Feng Jiao, Jing-Xue Liu, Adam Miranowicz, Yun-Lan Zuo, Le-Man Kuang, Hui Jing Vector optomechanical entanglement Nanophotonics, 11 (1), pp. 67–77, 2021. @article{Li2021, title = {Vector optomechanical entanglement}, author = {Ying Li and Ya-Feng Jiao and Jing-Xue Liu and Adam Miranowicz and Yun-Lan Zuo and Le-Man Kuang and Hui Jing}, url = {https://doi.org/10.1515/nanoph-2021-0485}, doi = {10.1515/nanoph-2021-0485}, year = {2021}, date = {2021-11-02}, journal = {Nanophotonics}, volume = {11}, number = {1}, pages = {67--77}, abstract = {The polarizations of optical fields, besides field intensities, provide more degrees of freedom to manipulate coherent light–matter interactions. Here, we propose how to achieve a coherent switch of optomechanical entanglement in a polarized-light-driven cavity system. We show that by tuning the polarizations of the driving field, the effective optomechanical coupling can be well controlled and, as a result, quantum entanglement between the mechanical oscillator and the optical transverse electric mode can be coherently and reversibly switched to that between the same phonon mode and the optical transverse magnetic mode. This ability to switch optomechanical entanglement with such a vectorial device can be important for building a quantum network being capable of efficient quantum information interchanges between processing nodes and flying photons.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The polarizations of optical fields, besides field intensities, provide more degrees of freedom to manipulate coherent light–matter interactions. Here, we propose how to achieve a coherent switch of optomechanical entanglement in a polarized-light-driven cavity system. We show that by tuning the polarizations of the driving field, the effective optomechanical coupling can be well controlled and, as a result, quantum entanglement between the mechanical oscillator and the optical transverse electric mode can be coherently and reversibly switched to that between the same phonon mode and the optical transverse magnetic mode. This ability to switch optomechanical entanglement with such a vectorial device can be important for building a quantum network being capable of efficient quantum information interchanges between processing nodes and flying photons. |
| 40. | Cătălin Paşcu Moca, Ireneusz Weymann, Miklós Antal Werner, Gergely Zaránd Kondo Cloud in a Superconductor Phys. Rev. Lett., 127 , pp. 186804, 2021. @article{Moca2021, title = {Kondo Cloud in a Superconductor}, author = {Cătălin Paşcu Moca and Ireneusz Weymann and Miklós Antal Werner and Gergely Zaránd}, url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.186804}, doi = {10.1103/PhysRevLett.127.186804}, year = {2021}, date = {2021-10-27}, journal = {Phys. Rev. Lett.}, volume = {127}, pages = {186804}, abstract = {Magnetic impurities embedded in a metal are screened by the Kondo effect, signaled by the formation of an extended correlation cloud, the so-called Kondo or screening cloud. In a superconductor, the Kondo state turns into subgap Yu-Shiba-Rusinov states, and a quantum phase transition occurs between screened and unscreened phases once the superconducting energy gap Δ exceeds sufficiently the Kondo temperature, TK. Here we show that, although the Kondo state does not form in the unscreened phase, the Kondo cloud does exist in both quantum phases. However, while screening is complete in the screened phase, it is only partial in the unscreened phase. Compensation, a quantity introduced to characterize the integrity of the cloud, is universal, and shown to be related to the magnetic impurities’ g factor, monitored experimentally by bias spectroscopy.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnetic impurities embedded in a metal are screened by the Kondo effect, signaled by the formation of an extended correlation cloud, the so-called Kondo or screening cloud. In a superconductor, the Kondo state turns into subgap Yu-Shiba-Rusinov states, and a quantum phase transition occurs between screened and unscreened phases once the superconducting energy gap Δ exceeds sufficiently the Kondo temperature, TK. Here we show that, although the Kondo state does not form in the unscreened phase, the Kondo cloud does exist in both quantum phases. However, while screening is complete in the screened phase, it is only partial in the unscreened phase. Compensation, a quantity introduced to characterize the integrity of the cloud, is universal, and shown to be related to the magnetic impurities’ g factor, monitored experimentally by bias spectroscopy. |
| 39. | Michal Mruczkiewicz, Paweł Gruszecki The 2021 roadmap for noncollinear magnonics Solid State Physics, 2021, ISSN: 0081-1947. @article{MRUCZKIEWICZ2021, title = {The 2021 roadmap for noncollinear magnonics}, author = {Michal Mruczkiewicz and Paweł Gruszecki}, url = {https://www.sciencedirect.com/science/article/pii/S0081194721000059}, doi = {https://doi.org/10.1016/bs.ssp.2021.09.001}, issn = {0081-1947}, year = {2021}, date = {2021-10-23}, journal = {Solid State Physics}, publisher = {Academic Press}, series = {Solid State Physics}, abstract = {Noncollinear magnonics is a rapidly developing topic of modern magnetism focusing on spin wave (magnon) dynamics in noncollinear spin textures. One of the driving forces of this research field is to employ nanosize dynamical noncollinear spin textures for the control and guiding of magnons. An unquestionable advantage of this approach is the potential to design programmable nanochannels with sizes below patterning limits. Furthermore, the noncollinear magnetic states induce nontrivial dynamical effects suitable for tailoring of SW propagation properties and emission of SWs. In the following, we will summarize the recent achievements of the field and discuss of current and future challenges.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Noncollinear magnonics is a rapidly developing topic of modern magnetism focusing on spin wave (magnon) dynamics in noncollinear spin textures. One of the driving forces of this research field is to employ nanosize dynamical noncollinear spin textures for the control and guiding of magnons. An unquestionable advantage of this approach is the potential to design programmable nanochannels with sizes below patterning limits. Furthermore, the noncollinear magnetic states induce nontrivial dynamical effects suitable for tailoring of SW propagation properties and emission of SWs. In the following, we will summarize the recent achievements of the field and discuss of current and future challenges. |
| 38. | Deng-Gao Lai, Wei Qin, Bang-Pin Hou, Adam Miranowicz, Franco Nori Phys. Rev. A, 104 , pp. 043521, 2021. @article{Lai2021, title = {Significant enhancement in refrigeration and entanglement in auxiliary-cavity-assisted optomechanical systems}, author = {Deng-Gao Lai and Wei Qin and Bang-Pin Hou and Adam Miranowicz and Franco Nori}, url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.104.043521}, doi = {10.1103/PhysRevA.104.043521}, year = {2021}, date = {2021-10-22}, journal = {Phys. Rev. A}, volume = {104}, pages = {043521}, abstract = {We propose how to achieve significantly enhanced quantum refrigeration and entanglement by coupling a pumped auxiliary cavity to an optomechanical cavity. We obtain both analytical and numerical results and find optimal-refrigeration and -entanglement conditions under the auxiliary-cavity-assisted (ACA) mechanism. Our method leads to a significant amplification in the net refrigeration rate and reveals that the ACA entanglement has a much stronger noise robustness in comparison with the unassisted case. By appropriately designing the ACA mechanism, an effective mechanical susceptibility can be well adjusted, and a genuine tripartite entanglement of cooling-cavity photons, auxiliary-cavity photons, and phonons can be generated. Specifically, we show that both optomechanical refrigeration and entanglement can be greatly enhanced for the blue-detuned driving of the auxiliary cavity but suppressed for the red-detuned case. Our work paves a way towards further quantum control of macroscopic mechanical systems and the enhancement and protection of fragile quantum resources.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We propose how to achieve significantly enhanced quantum refrigeration and entanglement by coupling a pumped auxiliary cavity to an optomechanical cavity. We obtain both analytical and numerical results and find optimal-refrigeration and -entanglement conditions under the auxiliary-cavity-assisted (ACA) mechanism. Our method leads to a significant amplification in the net refrigeration rate and reveals that the ACA entanglement has a much stronger noise robustness in comparison with the unassisted case. By appropriately designing the ACA mechanism, an effective mechanical susceptibility can be well adjusted, and a genuine tripartite entanglement of cooling-cavity photons, auxiliary-cavity photons, and phonons can be generated. Specifically, we show that both optomechanical refrigeration and entanglement can be greatly enhanced for the blue-detuned driving of the auxiliary cavity but suppressed for the red-detuned case. Our work paves a way towards further quantum control of macroscopic mechanical systems and the enhancement and protection of fragile quantum resources. |
| 37. | Mateusz Zelent, Iuliia V Vetrova, Jan Šoltýs, Xiaoguang Li, Yan Zhou, Vladislav A Gubanov, Alexandr V Sadovnikov, Tomas Šcepka, Jan Dérer, Roman Stoklas, Vladimír Cambel, Michal Mruczkiewicz Skyrmion Formation in Nanodisks Using Magnetic Force Microscopy Tip Nanomaterials, 11 (10), 2021, ISSN: 2079-4991. @article{nano11102627, title = {Skyrmion Formation in Nanodisks Using Magnetic Force Microscopy Tip}, author = {Mateusz Zelent and Iuliia V Vetrova and Jan Šoltýs and Xiaoguang Li and Yan Zhou and Vladislav A Gubanov and Alexandr V Sadovnikov and Tomas Šcepka and Jan Dérer and Roman Stoklas and Vladimír Cambel and Michal Mruczkiewicz}, url = {https://www.mdpi.com/2079-4991/11/10/2627}, doi = {10.3390/nano11102627}, issn = {2079-4991}, year = {2021}, date = {2021-10-06}, journal = {Nanomaterials}, volume = {11}, number = {10}, abstract = {We demonstrated numerically the skyrmion formation in ultrathin nanodisks using a magnetic force microscopy tip. We found that the local magnetic field generated by the magnetic tip significantly affects the magnetization state of the nanodisks and leads to the formation of skyrmions. Experimentally, we confirmed the influence of the local field on the magnetization states of the disks. Micromagnetic simulations explain the evolution of the magnetic state during magnetic force microscopy scanning and confirm the possibility of skyrmion formation. The formation of the horseshoe magnetic domain is a key transition from random labyrinth domain states into the skyrmion state. We showed that the formation of skyrmions by the magnetic probe is a reliable and repetitive procedure. Our findings provide a simple solution for skyrmion formation in nanodisks.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We demonstrated numerically the skyrmion formation in ultrathin nanodisks using a magnetic force microscopy tip. We found that the local magnetic field generated by the magnetic tip significantly affects the magnetization state of the nanodisks and leads to the formation of skyrmions. Experimentally, we confirmed the influence of the local field on the magnetization states of the disks. Micromagnetic simulations explain the evolution of the magnetic state during magnetic force microscopy scanning and confirm the possibility of skyrmion formation. The formation of the horseshoe magnetic domain is a key transition from random labyrinth domain states into the skyrmion state. We showed that the formation of skyrmions by the magnetic probe is a reliable and repetitive procedure. Our findings provide a simple solution for skyrmion formation in nanodisks. |