List of publications
Department of Mesoscopic Physics
Department of Quantum Information
Department of Physics of Nanostructures
Department of Theory of Condensed Matter
2025 |
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| 356. | Mateusz Zelent, Maciej Krawczyk, Konstantin Y Guslienko Beyond Fixed-Size Skyrmions in Nanodots: Switchable Multistability with Ferromagnetic Rings Nano Letters, 2025, ISSN: 1530-6984. @article{Zelent2025, title = {Beyond Fixed-Size Skyrmions in Nanodots: Switchable Multistability with Ferromagnetic Rings}, author = {Mateusz Zelent and Maciej Krawczyk and Konstantin Y Guslienko}, url = {https://doi.org/10.1021/acs.nanolett.5c02678}, doi = {10.1021/acs.nanolett.5c02678}, issn = {1530-6984}, year = {2025}, date = {2025-09-11}, journal = {Nano Letters}, publisher = {American Chemical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 355. | Lin Zhang, Igor Tyulnev, Lenard Vamos, Julita Poborska, Utso Bhattacharya, Ravindra W. Chhajlany, Tobias Grass, Jens Biegert, Maciej Lewenstein Revealing the anisotropic charge-density-wave order of $TiSe_2$ through high harmonic generation Phys. Rev. B, 112 , pp. 085147, 2025. @article{812z-nl4m, title = {Revealing the anisotropic charge-density-wave order of $TiSe_2$ through high harmonic generation}, author = {Lin Zhang and Igor Tyulnev and Lenard Vamos and Julita Poborska and Utso Bhattacharya and Ravindra W. Chhajlany and Tobias Grass and Jens Biegert and Maciej Lewenstein}, url = {https://link.aps.org/doi/10.1103/812z-nl4m}, doi = {10.1103/812z-nl4m}, year = {2025}, date = {2025-08-26}, journal = {Phys. Rev. B}, volume = {112}, pages = {085147}, publisher = {American Physical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 354. | Sebastião Antunes, Michal Stransky, Victor Tkachenko, Ichiro Inoue, Philip Heimann, Konrad J. Kapcia, Beata Ziaja Calculation of effective pump dose in X-ray-pump/X-ray-probe experiments Journal of Synchrotron Radiation, 32 (5), pp. 1106-1115, 2025. @article{Antunes2025, title = {Calculation of effective pump dose in X-ray-pump/X-ray-probe experiments}, author = {Sebastião Antunes and Michal Stransky and Victor Tkachenko and Ichiro Inoue and Philip Heimann and Konrad J. Kapcia and Beata Ziaja}, doi = {10.1107/S1600577525006939}, year = {2025}, date = {2025-08-21}, journal = {Journal of Synchrotron Radiation}, volume = {32}, number = {5}, pages = {1106-1115}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 353. | Kuba Chmielewski, Krzysztof Grygiel, Karol Bartkiewicz Stability Analysis of Three Coupled Kerr Oscillators: Implications for Quantum Computing CMST, 31 (1–3), pp. 33–47, 2025, ISSN: 1505-0602. @article{kuba_stability_2025, title = {Stability Analysis of Three Coupled Kerr Oscillators: Implications for Quantum Computing}, author = {Kuba Chmielewski and Krzysztof Grygiel and Karol Bartkiewicz }, url = {https://cmst.eu/articles/stability-analysis-of-three-coupled-kerr-oscillators-implications-for-quantum-computing/}, doi = {10.12921/cmst.2025.0000012}, issn = {1505-0602}, year = {2025}, date = {2025-08-18}, urldate = {2025-08-22}, journal = {CMST}, volume = {31}, number = {1–3}, pages = {33--47}, abstract = {We investigate the classical dynamics of optical nonlinear Kerr couplers, focusing on their potential relevance to quantum computing applications. The system consists of three Kerr-type nonlinear oscillators arranged in two configurations: a triangular arrangement, where each oscillator is coupled to the others, and a sandwich arrangement, where only the middle oscillator interacts with the two outer ones. The system is driven by an external periodic field and subject to dissipative processes. Its evolution is governed by six non-autonomous differential equations derived from a Kerr Hamiltonian with nonlinear coupling terms. We demonstrate that even for identical Kerr media, the interplay between nonlinear couplings and mismatched fundamental and pump frequencies gives rise to rich and complex dynamics, including the emergence of multiple stable attractors. These attractors are highly sensitive to both the coupling configuration and initial conditions. A key contribution of this work is a detailed stability analysis based on numerical calculation of Lyapunov exponents, revealing transitions from regular to chaotic dynamics as damping is reduced. We identify critical damping thresholds for the onset of chaos and characterize phenomena such as chaotic beats. These findings offer insights for potential experimental realizations and are directly relevant to emerging quantum technologies, where Kerr parametric oscillators play a central role in quantum gates, error correction protocols, and quantum neural network architectures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate the classical dynamics of optical nonlinear Kerr couplers, focusing on their potential relevance to quantum computing applications. The system consists of three Kerr-type nonlinear oscillators arranged in two configurations: a triangular arrangement, where each oscillator is coupled to the others, and a sandwich arrangement, where only the middle oscillator interacts with the two outer ones. The system is driven by an external periodic field and subject to dissipative processes. Its evolution is governed by six non-autonomous differential equations derived from a Kerr Hamiltonian with nonlinear coupling terms. We demonstrate that even for identical Kerr media, the interplay between nonlinear couplings and mismatched fundamental and pump frequencies gives rise to rich and complex dynamics, including the emergence of multiple stable attractors. These attractors are highly sensitive to both the coupling configuration and initial conditions. A key contribution of this work is a detailed stability analysis based on numerical calculation of Lyapunov exponents, revealing transitions from regular to chaotic dynamics as damping is reduced. We identify critical damping thresholds for the onset of chaos and characterize phenomena such as chaotic beats. These findings offer insights for potential experimental realizations and are directly relevant to emerging quantum technologies, where Kerr parametric oscillators play a central role in quantum gates, error correction protocols, and quantum neural network architectures. |
| 352. | O. M. Baksalary, G, Trenkler Another look at the eigenvalues of functions of a pair of orthogonal projectors Electronic Journal of Linear Algebra, 41 , pp. 412-424, 2025. @article{Baksalary2025b, title = {Another look at the eigenvalues of functions of a pair of orthogonal projectors}, author = {O. M. Baksalary and G, Trenkler}, doi = {10.13001/ela.2025.9331}, year = {2025}, date = {2025-08-12}, journal = {Electronic Journal of Linear Algebra}, volume = {41}, pages = {412-424}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 351. | Igor Tyulnev, Lin Zhang, Lenard Vamos, Julita Poborska, Utso Bhattacharya, Ravindra W. Chhajlany, Tobias Grass, Samuel Mañas-Valero, Eugenio Coronado, Maciej Lewenstein, Jens Biegert High harmonic spectroscopy reveals anisotropy of the charge-density-wave phase transition in TiSe2 Communications Materials, 6 (1), 2025, ISBN: 2662-4443. @article{Tyulnev2025, title = {High harmonic spectroscopy reveals anisotropy of the charge-density-wave phase transition in TiSe2}, author = {Igor Tyulnev and Lin Zhang and Lenard Vamos and Julita Poborska and Utso Bhattacharya and Ravindra W. Chhajlany and Tobias Grass and Samuel Mañas-Valero and Eugenio Coronado and Maciej Lewenstein and Jens Biegert}, url = {https://doi.org/10.1038/s43246-025-00873-5}, doi = {10.1038/s43246-025-00873-5}, isbn = {2662-4443}, year = {2025}, date = {2025-07-18}, journal = {Communications Materials}, volume = {6}, number = {1}, abstract = {Charge density waves (CDW) appear as periodic lattice deformations which arise from electron-phonon and excitonic correlations and provide a path towards the study of condensate phases at high temperatures. While characterization of this correlated phase is well established via real or reciprocal space techniques, for systems where the mechanisms interplay, a macroscopic approach becomes necessary. Here, we demonstrate the application of polarization-resolved high-harmonic generation (HHG) spectroscopy to investigate the correlated CDW phase and transitions in TiSe₂. Unlike previous studies focusing on static crystallographic properties, the research examines the dynamic reordering that occurs within the CDW as the material is cooled from room temperature to 14 K. By linking ultrafast field-driven dynamics to the material’s potential landscape, the study demonstrates HHG’s unique sensitivity to highly correlated phases and their strength. The findings reveal an anisotropic component below the CDW transition temperature, providing insights into the nature of this phase. The investigation highlights the interplay between linear and nonlinear optical responses and their departure from simple perturbative dynamics, offering a fresh perspective on correlated quantum phases in condensed matter systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Charge density waves (CDW) appear as periodic lattice deformations which arise from electron-phonon and excitonic correlations and provide a path towards the study of condensate phases at high temperatures. While characterization of this correlated phase is well established via real or reciprocal space techniques, for systems where the mechanisms interplay, a macroscopic approach becomes necessary. Here, we demonstrate the application of polarization-resolved high-harmonic generation (HHG) spectroscopy to investigate the correlated CDW phase and transitions in TiSe₂. Unlike previous studies focusing on static crystallographic properties, the research examines the dynamic reordering that occurs within the CDW as the material is cooled from room temperature to 14 K. By linking ultrafast field-driven dynamics to the material’s potential landscape, the study demonstrates HHG’s unique sensitivity to highly correlated phases and their strength. The findings reveal an anisotropic component below the CDW transition temperature, providing insights into the nature of this phase. The investigation highlights the interplay between linear and nonlinear optical responses and their departure from simple perturbative dynamics, offering a fresh perspective on correlated quantum phases in condensed matter systems. |
| 350. | Amrutha V. Achuthan, Sreedevi Janardhanan, Piotr Kuświk, Aleksandra Trzaskowska Scientific Reports, 15 (1), pp. 25585, 2025, ISSN: 2045-2322. @article{Achuthan2025, title = {Influence of effective thickness in elastic anisotropy and surface acoustic wave propagation in CoFeB/Au multilayer}, author = {Amrutha V. Achuthan and Sreedevi Janardhanan and Piotr Ku{ś}wik and Aleksandra Trzaskowska}, url = {https://doi.org/10.1038/s41598-025-08560-8}, doi = {10.1038/s41598-025-08560-8}, issn = {2045-2322}, year = {2025}, date = {2025-07-15}, journal = {Scientific Reports}, volume = {15}, number = {1}, pages = {25585}, abstract = {Surface acoustic waves (SAWs) in multilayered nanostructures represent a critical frontier in understanding material behavior at the nanoscale, with profound implications for emerging acoustic and spintronic technologies. In this study, we investigate the influence of the magnetic layer thickness on the propagation of surface acoustic waves in CoFeB-based multilayers. Two approaches to effective medium modelling are considered: treating the entire multilayer as a homogeneous medium and focusing on the region affected by light penetration. The elastic properties of the system are analyzed using Brillouin light scattering and numerical modelling, with a particular emphasis on the anisotropy of Young's modulus and its dependence on CoFeB thickness. The results reveal a significant variation in surface acoustic wave velocity and elastic anisotropy as a function of the multilayer configuration, highlighting the role of the penetration depth in effective medium approximations. The best agreement with BLS measurements was obtained for the effective medium model limited to the optical penetration depth, highlighting the importance of light-matter interaction volume in SAW-based diagnostics. These findings provide valuable insights into the tunability of acoustic and spin-wave frequencies through structural modifications, which is crucial for developing high-performance resonators, surface acoustic wave filters, and spin-wave-based information processing devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Surface acoustic waves (SAWs) in multilayered nanostructures represent a critical frontier in understanding material behavior at the nanoscale, with profound implications for emerging acoustic and spintronic technologies. In this study, we investigate the influence of the magnetic layer thickness on the propagation of surface acoustic waves in CoFeB-based multilayers. Two approaches to effective medium modelling are considered: treating the entire multilayer as a homogeneous medium and focusing on the region affected by light penetration. The elastic properties of the system are analyzed using Brillouin light scattering and numerical modelling, with a particular emphasis on the anisotropy of Young's modulus and its dependence on CoFeB thickness. The results reveal a significant variation in surface acoustic wave velocity and elastic anisotropy as a function of the multilayer configuration, highlighting the role of the penetration depth in effective medium approximations. The best agreement with BLS measurements was obtained for the effective medium model limited to the optical penetration depth, highlighting the importance of light-matter interaction volume in SAW-based diagnostics. These findings provide valuable insights into the tunability of acoustic and spin-wave frequencies through structural modifications, which is crucial for developing high-performance resonators, surface acoustic wave filters, and spin-wave-based information processing devices. |
| 349. | Emil Siuda, Ireneusz Weymann Competition between Nagaoka ferromagnetism and superconducting pairing in hybrid quantum dots Sci. Rep., 15 , pp. 25349, 2025. @article{Siuda2025c, title = {Competition between Nagaoka ferromagnetism and superconducting pairing in hybrid quantum dots}, author = {Emil Siuda and Ireneusz Weymann}, url = {https://www.nature.com/articles/s41598-025-10867-5}, doi = {/10.1038/s41598-025-10867-5}, year = {2025}, date = {2025-07-14}, journal = {Sci. Rep.}, volume = {15}, pages = {25349}, abstract = {We examine the interplay between the Nagaoka ferromagnetism and superconducting pairing correlations in a two-by-two quantum dot array proximitized by an s-wave superconductor. Focusing on the subgap regime, we determine the phase diagram of the system, demonstrating that Nagaoka ferromagnetism becomes greatly affected by the presence of superconductor and, depending on the strength of direct and crossed Andreev reflections, can be fully suppressed. This happens at some critical value of the induced on-dot pairing potential, for which we provide the corresponding analytical formulas in the limit of large Coulomb correlations. Moreover, we also shed light on the competition between Nagaoka ferromagnetism and superconductivity visible in the transport characteristics. Using the real-time diagrammatic technique, we determine the nonequilibrium current and differential conductance assuming that the quantum dot plaquette is weakly coupled to external lead that can be used to probe the system’s properties. We not only uncover the impact of Nagaoka ferromagnetism on the Andreev current and differential conductance, but also demonstrate a spin quintuplet blockade of the Andreev transport.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We examine the interplay between the Nagaoka ferromagnetism and superconducting pairing correlations in a two-by-two quantum dot array proximitized by an s-wave superconductor. Focusing on the subgap regime, we determine the phase diagram of the system, demonstrating that Nagaoka ferromagnetism becomes greatly affected by the presence of superconductor and, depending on the strength of direct and crossed Andreev reflections, can be fully suppressed. This happens at some critical value of the induced on-dot pairing potential, for which we provide the corresponding analytical formulas in the limit of large Coulomb correlations. Moreover, we also shed light on the competition between Nagaoka ferromagnetism and superconductivity visible in the transport characteristics. Using the real-time diagrammatic technique, we determine the nonequilibrium current and differential conductance assuming that the quantum dot plaquette is weakly coupled to external lead that can be used to probe the system’s properties. We not only uncover the impact of Nagaoka ferromagnetism on the Andreev current and differential conductance, but also demonstrate a spin quintuplet blockade of the Andreev transport. |
| 348. | Kacper Wrześniewski, Ireneusz Weymann Annalen der Physik, (e00236), 2025. @article{Wrześniewski2025, title = {Effects of Correlated Hopping on Thermoelectric Response of a Quantum dot Strongly Coupled to Ferromagnetic Leads}, author = {Kacper Wrześniewski and Ireneusz Weymann}, url = {https://onlinelibrary.wiley.com/doi/10.1002/andp.202500236}, doi = {10.1002/andp.202500236}, year = {2025}, date = {2025-07-05}, journal = {Annalen der Physik}, number = {e00236}, abstract = {The impact of correlated hopping on thermoelectric transport is theoretically investigated through a quantum dot coupled to ferromagnetic leads. Using the accurate numerical renormalization group method, the transport characteristics are analyzed, focusing on the interplay between electronic correlations, spin-dependent transport processes, and thermoelectric response. The electrical conductance and thermopower are calculated as functions of the dot energy level, lead polarization, and the amplitude of correlated hopping. Moreover, the effect of competing correlations is analyzed on the Kondo resonance and discuss the asymmetry of conductance peaks under the influence of the exchange field. It is demonstrated that the presence of correlated hopping is responsible for asymmetric spin-dependent transport characteristics. These results provide valuable insight into how correlated hopping affects spin-dependent transport and thermoelectric efficiency in quantum dot systems with ferromagnetic contacts.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The impact of correlated hopping on thermoelectric transport is theoretically investigated through a quantum dot coupled to ferromagnetic leads. Using the accurate numerical renormalization group method, the transport characteristics are analyzed, focusing on the interplay between electronic correlations, spin-dependent transport processes, and thermoelectric response. The electrical conductance and thermopower are calculated as functions of the dot energy level, lead polarization, and the amplitude of correlated hopping. Moreover, the effect of competing correlations is analyzed on the Kondo resonance and discuss the asymmetry of conductance peaks under the influence of the exchange field. It is demonstrated that the presence of correlated hopping is responsible for asymmetric spin-dependent transport characteristics. These results provide valuable insight into how correlated hopping affects spin-dependent transport and thermoelectric efficiency in quantum dot systems with ferromagnetic contacts. |
| 347. | Emil Siuda, Piotr Trocha Spin caloritronics of a quantum dot coupled to a magnetic insulator and normal metal Sci. Rep., 15 , pp. 23208, 2025. @article{Siuda2025b, title = {Spin caloritronics of a quantum dot coupled to a magnetic insulator and normal metal}, author = {Emil Siuda and Piotr Trocha}, url = {https://www.nature.com/articles/s41598-025-04413-6}, doi = {10.1038/s41598-025-04413-6}, year = {2025}, date = {2025-07-02}, journal = {Sci. Rep.}, volume = {15}, pages = {23208}, abstract = {We investigate the generation of spin current through temperature gradients in a quantum dot-based hybrid system. In particular, we study a quantum dot coupled to a magnetic insulator and a (non)magnetic metallic electrode. Generally, each electrode is maintained at a different temperature, resulting in a finite spin current. In this system, spin current of the magnonic type is converted into electric spin current, and vice versa, depending on the direction of the temperature gradient. We examine the influence of the magnonic energy-dependent density of states and many-body magnon interactions on thermally induced spin current. Additionally, the system can work as a spin Seebeck engine, converting heat into spin current. We establish the conditions under which the system operates as a heat engine and present results on its performance. Furthermore, we propose a device based on the system that acts as an efficient thermal spin-diode–allowing spin current to pass in one direction of the temperature bias while completely suppressing it in the opposite direction.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate the generation of spin current through temperature gradients in a quantum dot-based hybrid system. In particular, we study a quantum dot coupled to a magnetic insulator and a (non)magnetic metallic electrode. Generally, each electrode is maintained at a different temperature, resulting in a finite spin current. In this system, spin current of the magnonic type is converted into electric spin current, and vice versa, depending on the direction of the temperature gradient. We examine the influence of the magnonic energy-dependent density of states and many-body magnon interactions on thermally induced spin current. Additionally, the system can work as a spin Seebeck engine, converting heat into spin current. We establish the conditions under which the system operates as a heat engine and present results on its performance. Furthermore, we propose a device based on the system that acts as an efficient thermal spin-diode–allowing spin current to pass in one direction of the temperature bias while completely suppressing it in the opposite direction. |
| 346. | Lubomira Regeciova, Konrad J. Kapcia Localized fermions on the triangular lattice with Ising-like interactions Phys. Rev. E, 111 (6), pp. 064132, 2025. @article{Regeciova2025, title = {Localized fermions on the triangular lattice with Ising-like interactions}, author = {Lubomira Regeciova and Konrad J. Kapcia }, doi = {10.1103/4lmb-6qqv}, year = {2025}, date = {2025-06-24}, journal = {Phys. Rev. E}, volume = {111}, number = {6}, pages = {064132}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 345. | D. Maroulakos, C. Jasiukiewicz, A. Wal, A. Sinner, I. Weymann, T. Domański, L. Chotorlishvili Majorana signatures in the tripartite uncertainty relations with quantum memory Phys. Rev. B, 111 , pp. 224426, 2025. @article{Maroulakos2025, title = {Majorana signatures in the tripartite uncertainty relations with quantum memory}, author = {D. Maroulakos and C. Jasiukiewicz and A. Wal and A. Sinner and I. Weymann and T. Domański and L. Chotorlishvili}, url = {https://journals.aps.org/prb/abstract/10.1103/dxb2-15jf}, doi = {10.1103/dxb2-15jf}, year = {2025}, date = {2025-06-23}, journal = {Phys. Rev. B}, volume = {111}, pages = {224426}, abstract = {Quantumness imposes a fundamental limit on measurement accuracy. The paradigmatic cases are Heisenberg's uncertainty relation in the original formulation, Robertson's formulation, and improved uncertainty relations. However, the more universal measures are given in terms of quantum entropies. Uncertainties of measurements done on one quantum system correlated with another quantum system constitute a more intriguing question. Quantum correlations can influence the lower bound of uncertainties, and the reason for this is the quantum memory. In this article, we study uncertainties of measurements performed on one quantum dot correlated with the second one through the superconductor, hosting the Majorana boundary modes. We prove that the Majorana quasiparticles allow the uncertainties to reach the minimal possible lower bound. By rigorous theoretical considerations, we obtain the result of experimental relevance expressed in terms of only two parameters: the overlap between Majorana modes and their coupling strength with the quantum dots. We show that the overlap between Majorana modes reduces quantum uncertainties, which is a general result of fundamental importance. We also propose the protocol to measure spins in both quantum dots, consecutively, and demonstrate that the result of the second measurement would depend on the presence of Majorana quasiparticles. This could serve as an indirect tool for their empirical observation, which is of importance for the ongoing discussions concerning unambiguous detection of the Majorana quasiparticles in nanoscopic hybrid structures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Quantumness imposes a fundamental limit on measurement accuracy. The paradigmatic cases are Heisenberg's uncertainty relation in the original formulation, Robertson's formulation, and improved uncertainty relations. However, the more universal measures are given in terms of quantum entropies. Uncertainties of measurements done on one quantum system correlated with another quantum system constitute a more intriguing question. Quantum correlations can influence the lower bound of uncertainties, and the reason for this is the quantum memory. In this article, we study uncertainties of measurements performed on one quantum dot correlated with the second one through the superconductor, hosting the Majorana boundary modes. We prove that the Majorana quasiparticles allow the uncertainties to reach the minimal possible lower bound. By rigorous theoretical considerations, we obtain the result of experimental relevance expressed in terms of only two parameters: the overlap between Majorana modes and their coupling strength with the quantum dots. We show that the overlap between Majorana modes reduces quantum uncertainties, which is a general result of fundamental importance. We also propose the protocol to measure spins in both quantum dots, consecutively, and demonstrate that the result of the second measurement would depend on the presence of Majorana quasiparticles. This could serve as an indirect tool for their empirical observation, which is of importance for the ongoing discussions concerning unambiguous detection of the Majorana quasiparticles in nanoscopic hybrid structures. |
| 344. | Anand Manaparambil, Cǎtǎlin Paşcu Moca, Gergely Zaránd, Ireneusz Weymann Underscreened Kondo compensation in a superconductor Phys. Rev. B, 111 , pp. 235433, 2025. @article{Manaparambil2025b, title = {Underscreened Kondo compensation in a superconductor}, author = {Anand Manaparambil and Cǎtǎlin Paşcu Moca and Gergely Zaránd and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/j7b4-ywmp}, doi = {10.1103/j7b4-ywmp}, year = {2025}, date = {2025-06-16}, journal = {Phys. Rev. B}, volume = {111}, pages = {235433}, abstract = {A magnetic impurity with a larger 𝑆=1 spin remains partially screened by the Kondo effect when embedded in a metal. However, when placed within an 𝑠-wave superconductor, the interplay between the superconducting energy gap Δ and the Kondo temperature 𝑇𝐾 induces a quantum phase transition from an underscreened doublet Kondo to an unscreened triplet phase, typically occurring when Δ/𝑇𝐾≈1. We investigate the Kondo compensation of the impurity spin resulting from this partial screening across the quantum phase transition, which together with the spin-spin correlation function serves as a measure of the Kondo cloud's integrity. Deep within the unscreened triplet phase, Δ/𝑇𝐾≫1, the compensation vanishes, signifying complete decoupling of the impurity spin from the environment, while in the partially screened doublet phase, Δ/𝑇𝐾≪1, it asymptotically approaches 1/2, indicating that half of the spin is screened. Notably, there is a universal jump in the compensation precisely at the phase transition, which we accurately calculate. The spin-spin correlation function exhibits an oscillatory pattern with an envelope function decaying as ≈1/𝑥 at short distances. At larger distances, the superconducting gap induces an exponentially decaying behavior ≈exp(−𝑥/𝜉Δ) governed by the superconducting correlation length 𝜉Δ, irrespective of the phase, without any distinctive features across the transition. Furthermore, the spectral functions of some relevant operators are evaluated and discussed. In terms of the methods used, a consistent description is provided through the application of multiplicative, numerical, and density-matrix renormalization group techniques.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A magnetic impurity with a larger 𝑆=1 spin remains partially screened by the Kondo effect when embedded in a metal. However, when placed within an 𝑠-wave superconductor, the interplay between the superconducting energy gap Δ and the Kondo temperature 𝑇𝐾 induces a quantum phase transition from an underscreened doublet Kondo to an unscreened triplet phase, typically occurring when Δ/𝑇𝐾≈1. We investigate the Kondo compensation of the impurity spin resulting from this partial screening across the quantum phase transition, which together with the spin-spin correlation function serves as a measure of the Kondo cloud's integrity. Deep within the unscreened triplet phase, Δ/𝑇𝐾≫1, the compensation vanishes, signifying complete decoupling of the impurity spin from the environment, while in the partially screened doublet phase, Δ/𝑇𝐾≪1, it asymptotically approaches 1/2, indicating that half of the spin is screened. Notably, there is a universal jump in the compensation precisely at the phase transition, which we accurately calculate. The spin-spin correlation function exhibits an oscillatory pattern with an envelope function decaying as ≈1/𝑥 at short distances. At larger distances, the superconducting gap induces an exponentially decaying behavior ≈exp(−𝑥/𝜉Δ) governed by the superconducting correlation length 𝜉Δ, irrespective of the phase, without any distinctive features across the transition. Furthermore, the spectral functions of some relevant operators are evaluated and discussed. In terms of the methods used, a consistent description is provided through the application of multiplicative, numerical, and density-matrix renormalization group techniques. |
| 343. | Javid Naikoo, Ravindra W. Chhajlany, Adam Miranowicz Enhanced quantum sensing with hybrid exceptional-diabolic singularities New Journal of Physics, 27 (6), pp. 064505, 2025. @article{Naikoo_2025, title = {Enhanced quantum sensing with hybrid exceptional-diabolic singularities}, author = {Javid Naikoo and Ravindra W. Chhajlany and Adam Miranowicz}, url = {https://dx.doi.org/10.1088/1367-2630/addc12}, doi = {10.1088/1367-2630/addc12}, year = {2025}, date = {2025-06-01}, journal = {New Journal of Physics}, volume = {27}, number = {6}, pages = {064505}, publisher = {IOP Publishing}, abstract = {We report an enhanced sensitivity for detecting linear perturbations near hybrid (doubly degenerated) exceptional-diabolic (HED) singular points in a four mode bosonic system. The sensitivity enhancement is attributed to a singular response function, with the pole order determining the scaling of estimation error. At HED singular points, the error scaling exhibits a twofold improvement over non-HED singular points. The ultimate bound on estimation error is derived via quantum Fisher information, with heterodyne detection identified as the measurement achieving this optimal scaling.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report an enhanced sensitivity for detecting linear perturbations near hybrid (doubly degenerated) exceptional-diabolic (HED) singular points in a four mode bosonic system. The sensitivity enhancement is attributed to a singular response function, with the pole order determining the scaling of estimation error. At HED singular points, the error scaling exhibits a twofold improvement over non-HED singular points. The ultimate bound on estimation error is derived via quantum Fisher information, with heterodyne detection identified as the measurement achieving this optimal scaling. |
| 342. | Ephraim T Mathew, Andriy E. Serebryannikov, Jacek Jenczyk, Igor Iatsunskyi, Szymon Murawka, Mikołaj Lewandowski, Maciej Wiesner ACS Applied Materials & Interfaces, 2025, ISSN: 1944-8244. @article{Mathew2025, title = {Raman Scattering Enhancements Due to Super- and Subradiant Collective Plasmon Modes on Large-Area 2D-Au Arrays}, author = {Ephraim T Mathew and Andriy E. Serebryannikov and Jacek Jenczyk and Igor Iatsunskyi and Szymon Murawka and Mikołaj Lewandowski and Maciej Wiesner }, url = {https://doi.org/10.1021/acsami.5c04804}, doi = {10.1021/acsami.5c04804}, issn = {1944-8244}, year = {2025}, date = {2025-05-22}, journal = {ACS Applied Materials & Interfaces}, publisher = {American Chemical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 341. | Sara Memarzadeh, Mateusz Gołębiewski, Maciej Krawczyk, Jarosław W. Kłos Nucleation and arrangement of Abrikosov vortices in hybrid superconductor–ferromagnet nanostructures Nanoscale Horiz., 10 , pp. 1453 - 1464, 2025. @article{D4NH00618F, title = {Nucleation and arrangement of Abrikosov vortices in hybrid superconductor–ferromagnet nanostructures}, author = {Sara Memarzadeh and Mateusz Gołębiewski and Maciej Krawczyk and Jarosław W. Kłos}, url = {http://dx.doi.org/10.1039/D4NH00618F}, doi = {10.1039/D4NH00618F}, year = {2025}, date = {2025-05-21}, journal = {Nanoscale Horiz.}, volume = {10}, pages = {1453 - 1464}, publisher = {The Royal Society of Chemistry}, abstract = {This study investigates the nucleation, dynamics, and stationary configurations of Abrikosov vortices in hybrid superconductor–ferromagnet nanostructures subjected to inhomogeneous magnetic fields generated by a ferromagnetic nanodot. Employing the simulations based on time-dependent Ginzburg–Landau coupled with Maxwell's equations, we reveal the evolution of curved vortex structures that exhibit creep-like deformation before stabilizing. The interplay between vortices and currents confined within the superconducting nanoelement gives rise to unconventional stationary vortex arrangements, which evolve gradually with increasing magnetic field strength—a behavior absent in homogeneous fields. Our numerical results illustrate how the ferromagnetic element can control vortex configurations via a stray magnetic field—insights that are difficult to access experimentally or analytically. We demonstrate that the superconducting nanoelement can stabilize into distinct vortex states in response to even small system perturbations. This highlights the extreme sensitivity of the system and the richness of its dynamic behaviour, revealing complex pinning mechanisms and providing valuable insights into the optimisation of nanoscale superconducting systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This study investigates the nucleation, dynamics, and stationary configurations of Abrikosov vortices in hybrid superconductor–ferromagnet nanostructures subjected to inhomogeneous magnetic fields generated by a ferromagnetic nanodot. Employing the simulations based on time-dependent Ginzburg–Landau coupled with Maxwell's equations, we reveal the evolution of curved vortex structures that exhibit creep-like deformation before stabilizing. The interplay between vortices and currents confined within the superconducting nanoelement gives rise to unconventional stationary vortex arrangements, which evolve gradually with increasing magnetic field strength—a behavior absent in homogeneous fields. Our numerical results illustrate how the ferromagnetic element can control vortex configurations via a stray magnetic field—insights that are difficult to access experimentally or analytically. We demonstrate that the superconducting nanoelement can stabilize into distinct vortex states in response to even small system perturbations. This highlights the extreme sensitivity of the system and the richness of its dynamic behaviour, revealing complex pinning mechanisms and providing valuable insights into the optimisation of nanoscale superconducting systems. |
| 340. | Kuan-Yi Lee, Jhen-Dong Lin, Karel Lemr, Antonín Černoch, Adam Miranowicz, Franco Nori, Huan-Yu Ku, Yueh-Nan Chen Unveiling quantum steering by quantum-classical uncertainty complementarity npj Quantum Information, 11 (1), pp. 72, 2025, ISSN: 2056-6387. @article{Lee2025, title = {Unveiling quantum steering by quantum-classical uncertainty complementarity}, author = {Kuan-Yi Lee and Jhen-Dong Lin and Karel Lemr and Antonín {Č}ernoch and Adam Miranowicz and Franco Nori and Huan-Yu Ku and Yueh-Nan Chen}, url = {https://doi.org/10.1038/s41534-025-01017-w}, doi = {10.1038/s41534-025-01017-w}, issn = {2056-6387}, year = {2025}, date = {2025-05-08}, journal = {npj Quantum Information}, volume = {11}, number = {1}, pages = {72}, abstract = {One of the remarkable aspects of quantum steering is its ability to violate local uncertainty complementarity relations. In this vein of study, various steering witnesses have been developed. Here, we introduce a novel complementarity relation between the system's quantum and classical uncertainties corresponding to the distillable coherence and the von Neumann entropy, respectively. We show that the proposed complementarity relation is tighter than the entropic uncertainty relation (EUR). Leveraging this result, we propose a steering witness that is more efficient than the EUR. From the operational perspective, the steering witness quantifies the amount of extra distillable coherence facilitated by quantum steerability. Notably, the proposed steering witness serves as a full entanglement measure for pure bipartite states--an ability that the EUR lacks. We also experimentally validate such a property through a photonic system. Furthermore, a deeper connection to the uncertainty principle is revealed by showcasing the steering-induced distillable coherence can quantify measurement incompatibility and quantum steerability under genuine incoherent operations. Our work establishes a clear quantitative and operational link between coherence and steering, which are vital resources of quantum technologies, and underscores our efforts in bridging the uncertainty principle with quantum coherence.}, keywords = {}, pubstate = {published}, tppubtype = {article} } One of the remarkable aspects of quantum steering is its ability to violate local uncertainty complementarity relations. In this vein of study, various steering witnesses have been developed. Here, we introduce a novel complementarity relation between the system's quantum and classical uncertainties corresponding to the distillable coherence and the von Neumann entropy, respectively. We show that the proposed complementarity relation is tighter than the entropic uncertainty relation (EUR). Leveraging this result, we propose a steering witness that is more efficient than the EUR. From the operational perspective, the steering witness quantifies the amount of extra distillable coherence facilitated by quantum steerability. Notably, the proposed steering witness serves as a full entanglement measure for pure bipartite states--an ability that the EUR lacks. We also experimentally validate such a property through a photonic system. Furthermore, a deeper connection to the uncertainty principle is revealed by showcasing the steering-induced distillable coherence can quantify measurement incompatibility and quantum steerability under genuine incoherent operations. Our work establishes a clear quantitative and operational link between coherence and steering, which are vital resources of quantum technologies, and underscores our efforts in bridging the uncertainty principle with quantum coherence. |
| 339. | Chia-Yi Ju, Adam Miranowicz, Jacob Barnett, Guang-Yin Chen, Franco Nori Phys. Rev. A, 111 , pp. 052213, 2025. @article{Ju25, title = {Heisenberg and Heisenberg-like representations via Hilbert-space-bundle geometry in the non-Hermitian regime}, author = {Chia-Yi Ju and Adam Miranowicz and Jacob Barnett and Guang-Yin Chen and Franco Nori}, url = {https://link.aps.org/doi/10.1103/PhysRevA.111.052213}, doi = {10.1103/PhysRevA.111.052213}, year = {2025}, date = {2025-05-01}, journal = {Phys. Rev. A}, volume = {111}, pages = {052213}, publisher = {American Physical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 338. | Przemysław Chełminiak, Jan Wójcik, Antoni Wójcik Physical Review E, 111 (4), pp. 044143 , 2025. @article{Chełminiak2025, title = {Discrete-time walk on one-dimensional lattice under stochastic resetting: Advantage of quantum over classical scenario}, author = {Przemysław Chełminiak and Jan Wójcik and Antoni Wójcik}, doi = {10.1103/PhysRevE.111.044143}, year = {2025}, date = {2025-04-30}, journal = {Physical Review E}, volume = {111}, number = {4}, pages = {044143 }, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 337. | Vrishali Sonar, Piotr Trocha Sci. Rep., 15 , pp. 14509, 2025. @article{Sonar2025, title = {Spin dependent thermoelectric transport in a multiterminal quantum dot hybrid including a superconductor and ferromagnets}, author = {Vrishali Sonar and Piotr Trocha}, url = {https://www.nature.com/articles/s41598-025-94991-2}, doi = {10.1038/s41598-025-94991-2}, year = {2025}, date = {2025-04-25}, journal = {Sci. Rep.}, volume = {15}, pages = {14509}, abstract = {We investigate the thermoelectric response of a hybrid system consisting of two ferromagnetic electrodes and one superconducting lead coupled to a single-level quantum dot with finite Coulomb repulsion. Using the non-equilibrium Green’s function technique within the Hubbard-I approximation, local and non-local thermoelectric coefficients, along with their spin counterparts, such as electrical and thermal conductance, and the Seebeck coefficient are calculated up to linear order with respect to generalized forces. Here, we present a derivation of spin-dependent thermoelectric coefficients for a three-terminal system, extending the existing theory which allowed to describe only cases independent of spin-bias voltage, i.e. when spin accumulation is irrelevant. In the considered system, four competing processes- single particle tunneling, quasiparticle tunneling, direct and crossed Andreev reflection make the system highly adaptable for tuning charge and heat currents. A full analysis of their impact on thermoelectric effects is provided. Moreover, the output power and efficiency of the system operating as a heat engine are evaluated. The extensive goal of this work is to demonstrate how the presence of an additional terminal modifies the hybrid QD-based device’s performance and under which conditions non-local thermoelectric effects become significant.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate the thermoelectric response of a hybrid system consisting of two ferromagnetic electrodes and one superconducting lead coupled to a single-level quantum dot with finite Coulomb repulsion. Using the non-equilibrium Green’s function technique within the Hubbard-I approximation, local and non-local thermoelectric coefficients, along with their spin counterparts, such as electrical and thermal conductance, and the Seebeck coefficient are calculated up to linear order with respect to generalized forces. Here, we present a derivation of spin-dependent thermoelectric coefficients for a three-terminal system, extending the existing theory which allowed to describe only cases independent of spin-bias voltage, i.e. when spin accumulation is irrelevant. In the considered system, four competing processes- single particle tunneling, quasiparticle tunneling, direct and crossed Andreev reflection make the system highly adaptable for tuning charge and heat currents. A full analysis of their impact on thermoelectric effects is provided. Moreover, the output power and efficiency of the system operating as a heat engine are evaluated. The extensive goal of this work is to demonstrate how the presence of an additional terminal modifies the hybrid QD-based device’s performance and under which conditions non-local thermoelectric effects become significant. |
| 336. | Vrishali Sonar, Piotr Trocha Scientific Reports, 15 (1), pp. 14509, 2025, ISSN: 2045-2322. @article{sonar_spin_2025, title = {Spin dependent thermoelectric transport in a multiterminal quantum dot hybrid including a superconductor and ferromagnets}, author = {Vrishali Sonar and Piotr Trocha}, url = {https://www.nature.com/articles/s41598-025-94991-2}, doi = {10.1038/s41598-025-94991-2}, issn = {2045-2322}, year = {2025}, date = {2025-04-25}, urldate = {2025-05-30}, journal = {Scientific Reports}, volume = {15}, number = {1}, pages = {14509}, abstract = {We investigate the thermoelectric response of a hybrid system consisting of two ferromagnetic electrodes and one superconducting lead coupled to a single-level quantum dot with finite Coulomb repulsion. Using the non-equilibrium Green’s function technique within the Hubbard-I approximation, local and non-local thermoelectric coefficients, along with their spin counterparts, such as electrical and thermal conductance, and the Seebeck coefficient are calculated up to linear order with respect to generalized forces. Here, we present a derivation of spin-dependent thermoelectric coefficients for a three-terminal system, extending the existing theory which allowed to describe only cases independent of spin-bias voltage, i.e. when spin accumulation is irrelevant. In the considered system, four competing processes- single particle tunneling, quasiparticle tunneling, direct and crossed Andreev reflection make the system highly adaptable for tuning charge and heat currents. A full analysis of their impact on thermoelectric effects is provided. Moreover, the output power and efficiency of the system operating as a heat engine are evaluated. The extensive goal of this work is to demonstrate how the presence of an additional terminal modifies the hybrid QD-based device’s performance and under which conditions non-local thermoelectric effects become significant.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate the thermoelectric response of a hybrid system consisting of two ferromagnetic electrodes and one superconducting lead coupled to a single-level quantum dot with finite Coulomb repulsion. Using the non-equilibrium Green’s function technique within the Hubbard-I approximation, local and non-local thermoelectric coefficients, along with their spin counterparts, such as electrical and thermal conductance, and the Seebeck coefficient are calculated up to linear order with respect to generalized forces. Here, we present a derivation of spin-dependent thermoelectric coefficients for a three-terminal system, extending the existing theory which allowed to describe only cases independent of spin-bias voltage, i.e. when spin accumulation is irrelevant. In the considered system, four competing processes- single particle tunneling, quasiparticle tunneling, direct and crossed Andreev reflection make the system highly adaptable for tuning charge and heat currents. A full analysis of their impact on thermoelectric effects is provided. Moreover, the output power and efficiency of the system operating as a heat engine are evaluated. The extensive goal of this work is to demonstrate how the presence of an additional terminal modifies the hybrid QD-based device’s performance and under which conditions non-local thermoelectric effects become significant. |
| 335. | Christian Brahms, Lin Zhang, Xiao Shen, Utso Bhattacharya, Maria Recasens, Johann Osmond, Tobias Grass, Ravindra W. Chhajlany, Kent A Hallman, Richard F Haglund, Sokrates T Pantelides, Maciej Lewenstein, John C Travers, Allan S Johnson Decoupled few-femtosecond phase transitions in vanadium dioxide Nature Communications, 16 (1), pp. 3714, 2025, ISBN: 2041-1723. @article{Brahms2025, title = {Decoupled few-femtosecond phase transitions in vanadium dioxide}, author = {Christian Brahms and Lin Zhang and Xiao Shen and Utso Bhattacharya and Maria Recasens and Johann Osmond and Tobias Grass and Ravindra W. Chhajlany and Kent A Hallman and Richard F Haglund and Sokrates T Pantelides and Maciej Lewenstein and John C Travers and Allan S Johnson}, url = {https://doi.org/10.1038/s41467-025-58895-z}, doi = {10.1038/s41467-025-58895-z}, isbn = {2041-1723}, year = {2025}, date = {2025-04-19}, journal = {Nature Communications}, volume = {16}, number = {1}, pages = {3714}, abstract = {The nature of the insulator-to-metal phase transition in vanadium dioxide (VO2) is one of the longest-standing problems in condensed-matter physics. Ultrafast spectroscopy has long promised to determine whether the transition is primarily driven by the electronic or structural degree of freedom, but measurements to date have been stymied by their sensitivity to only one of these components and/or their limited temporal resolution. Here we use ultra-broadband few-femtosecond pump-probe spectroscopy to resolve the electronic and structural phase transitions in VO2 at their fundamental time scales. Our experiments show that the system transforms into a bad-metallic phase within 10 fs after photoexcitation, but requires another 100 fs to complete the transition, during which we observe electronic oscillations and a partial re-opening of the bandgap, signalling a transient semi-metallic state. Comparisons with tensor-network simulations and density-functional theory calculations show these features result from an unexpectedly fast structural transition, in which the vanadium dimers separate and untwist with two different timescales. Our results resolve the structural and electronic nature of the light-induced phase transition in VO2 and establish ultra-broadband few-femtosecond spectroscopy as a powerful tool for studying quantum materials out of equilibrium.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The nature of the insulator-to-metal phase transition in vanadium dioxide (VO2) is one of the longest-standing problems in condensed-matter physics. Ultrafast spectroscopy has long promised to determine whether the transition is primarily driven by the electronic or structural degree of freedom, but measurements to date have been stymied by their sensitivity to only one of these components and/or their limited temporal resolution. Here we use ultra-broadband few-femtosecond pump-probe spectroscopy to resolve the electronic and structural phase transitions in VO2 at their fundamental time scales. Our experiments show that the system transforms into a bad-metallic phase within 10 fs after photoexcitation, but requires another 100 fs to complete the transition, during which we observe electronic oscillations and a partial re-opening of the bandgap, signalling a transient semi-metallic state. Comparisons with tensor-network simulations and density-functional theory calculations show these features result from an unexpectedly fast structural transition, in which the vanadium dimers separate and untwist with two different timescales. Our results resolve the structural and electronic nature of the light-induced phase transition in VO2 and establish ultra-broadband few-femtosecond spectroscopy as a powerful tool for studying quantum materials out of equilibrium. |
| 334. | Csanád Hajdú, Cătălin Paşcu Moca, Balázs Dóra, Ireneusz Weymann, Gergely Zaránd Kondo compensation in a pseudogap phase: A renormalization group study Phys. Rev. B, 111 , pp. 155125, 2025. @article{Hajdú2025, title = {Kondo compensation in a pseudogap phase: A renormalization group study}, author = {Csanád Hajdú and Cătălin Paşcu Moca and Balázs Dóra and Ireneusz Weymann and Gergely Zaránd}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.111.155125}, doi = {10.1103/PhysRevB.111.155125}, year = {2025}, date = {2025-04-15}, journal = {Phys. Rev. B}, volume = {111}, pages = {155125}, abstract = {We investigate the critical behavior of the Kondo compensation in the presence of a power-law pseudogap in the density of states, 𝜌(𝜔)∼|𝜔|𝜀. For 𝜀<1, generically—in the absence of particle-hole symmetry—this model exhibits a quantum phase transition from a partially screened doublet ground state to a fully screened many-body ground state upon increasing the exchange coupling 𝑗. At the critical point 𝑗c, the Kondo compensation is found to scale as 𝜅(𝑗<𝑗c)=1−𝑔(𝑗) with the local 𝑔-factor vanishing as 𝑔∼|𝑗−𝑗c|^𝛽. We combine the perturbative drone fermion method with the nonperturbative numerical renormalization group computations to determine the critical exponent 𝛽(𝜀), which exhibits a nonmonotonous behavior as a function of 𝜀. Our results confirm that the Kondo cloud builds up continuously in the presence of a weak pseudogap as one approaches the phase transition.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate the critical behavior of the Kondo compensation in the presence of a power-law pseudogap in the density of states, 𝜌(𝜔)∼|𝜔|𝜀. For 𝜀<1, generically—in the absence of particle-hole symmetry—this model exhibits a quantum phase transition from a partially screened doublet ground state to a fully screened many-body ground state upon increasing the exchange coupling 𝑗. At the critical point 𝑗c, the Kondo compensation is found to scale as 𝜅(𝑗<𝑗c)=1−𝑔(𝑗) with the local 𝑔-factor vanishing as 𝑔∼|𝑗−𝑗c|^𝛽. We combine the perturbative drone fermion method with the nonperturbative numerical renormalization group computations to determine the critical exponent 𝛽(𝜀), which exhibits a nonmonotonous behavior as a function of 𝜀. Our results confirm that the Kondo cloud builds up continuously in the presence of a weak pseudogap as one approaches the phase transition. |
| 333. | Ichiro Inoue, Taito Osaka, Victor Tkachenko, Toru Hara, Konrad J. Kapcia, Yuichi Inubushi, Shogo Kawaguchi, Jumpei Yamada, Eiji Nishibori, Makina Yabashi, Beata Ziaja High-intensity X-ray pump-monochromatic X-ray probe technique across time zero Optica, 12 (4), pp. 530-533, 2025, ISSN: 2334-2536. @article{Inoue2025, title = {High-intensity X-ray pump-monochromatic X-ray probe technique across time zero}, author = {Ichiro Inoue and Taito Osaka and Victor Tkachenko and Toru Hara and Konrad J. Kapcia and Yuichi Inubushi and Shogo Kawaguchi and Jumpei Yamada and Eiji Nishibori and Makina Yabashi and Beata Ziaja}, doi = {10.1364/OPTICA.555433}, issn = {2334-2536}, year = {2025}, date = {2025-04-15}, journal = {Optica}, volume = {12}, number = {4}, pages = {530-533}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 332. | Przemysław Chełminiak, Jan Wójcik, Antoni Wójcik Phys. Rev. E, 111 , pp. 044143, 2025. @article{PhysRevE.111.044143, title = {Discrete-time walk on one-dimensional lattice under stochastic resetting: Advantage of quantum over classical scenario}, author = {Przemysław Chełminiak and Jan Wójcik and Antoni Wójcik}, url = {https://link.aps.org/doi/10.1103/PhysRevE.111.044143}, doi = {10.1103/PhysRevE.111.044143}, year = {2025}, date = {2025-04-01}, journal = {Phys. Rev. E}, volume = {111}, pages = {044143}, publisher = {American Physical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 331. | O. M. Baksalary, D. Bernstein The Rao-Mitra-Bhimasankaram relation is strongly antisymmetric Linear Algebra and its Applications, 710 , pp. 80-94, 2025. @article{Baksalary2025, title = {The Rao-Mitra-Bhimasankaram relation is strongly antisymmetric}, author = {O. M. Baksalary and D. Bernstein}, doi = {10.1016/j.laa.2025.01.029}, year = {2025}, date = {2025-04-01}, journal = {Linear Algebra and its Applications}, volume = {710}, pages = {80-94}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 330. | Jian Tang, Yunlan Zuo, Xun-Wei Xu, Ran Huang, Adam Miranowicz, Franco Nori, Hui Jing Achieving Robust Single-Photon Blockade with a Single Nanotip Nano Letters, 25 (12), pp. 4705-4712, 2025, ISSN: 1530-6984. @article{Tang2025, title = {Achieving Robust Single-Photon Blockade with a Single Nanotip}, author = {Jian Tang and Yunlan Zuo and Xun-Wei Xu and Ran Huang and Adam Miranowicz and Franco Nori and Hui Jing}, url = {https://doi.org/10.1021/acs.nanolett.4c05433}, doi = {10.1021/acs.nanolett.4c05433}, issn = {1530-6984}, year = {2025}, date = {2025-03-26}, journal = {Nano Letters}, volume = {25}, number = {12}, pages = {4705-4712}, publisher = {American Chemical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 329. | Lin Zhang, Utso Bhattacharya, Maria Recasens, Tobias Grass, Ravindra W. Chhajlany, Maciej Lewenstein, Allan S Johnson Tensor network study of the light-induced phase transitions in vanadium dioxide npj Quantum Materials, 10 (1), pp. 32, 2025, ISBN: 2397-4648. @article{Zhang2025, title = {Tensor network study of the light-induced phase transitions in vanadium dioxide}, author = {Lin Zhang and Utso Bhattacharya and Maria Recasens and Tobias Grass and Ravindra W. Chhajlany and Maciej Lewenstein and Allan S Johnson}, url = {https://doi.org/10.1038/s41535-025-00751-w}, doi = {10.1038/s41535-025-00751-w}, isbn = {2397-4648}, year = {2025}, date = {2025-03-24}, journal = {npj Quantum Materials}, volume = {10}, number = {1}, pages = {32}, abstract = {Vanadium dioxide (VO2) is a prototypical material that undergoes a structural phase transition (SPT) from a monoclinic (M1) to rutile (R) structure and an insulator-to-metal transition (IMT) when heated above 340 K or excited by an ultrafast laser pulse. Due to the strong electron–electron and electron–lattice interactions, modeling the ultrafast IMT in VO2 has proven challenging. Here, we develop an efficient theoretical approach to the light-induced phase transitions by combining a tensor network ansatz for the electrons with a semiclassical description of the nuclei. Our method is based on a quasi-one-dimensional model for the material with the important multiorbital character, electron–lattice coupling, and electron–electron correlations being included. We benchmark our method by showing that it qualitatively captures the ground state phase diagram and finite-temperature phase transitions of VO2. Then, we use the hybrid quantum-classical tensor network approach to simulate the dynamics following photoexcitation. We find that the structure can transform faster than the harmonic phonon modes of the M1 phase, suggesting lattice nonlinearity is key in the SPT. We also find separate timescales in the evolution of dimerization and tilt lattice distortions, as well as the loss and subsequent partial restoration behavior of the displacements, explaining the complex dynamics observed in recent experiments. Moreover, decoupled SPT and IMT dynamics are observed, with the IMT occurs quasi-instantaneously. Our model and approach, which can be extended to a wide range of materials, reveal the unexpected non-monotonic transformation pathways in VO2 and pave the way for future studies of non-thermal phase transformations in quantum materials.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Vanadium dioxide (VO2) is a prototypical material that undergoes a structural phase transition (SPT) from a monoclinic (M1) to rutile (R) structure and an insulator-to-metal transition (IMT) when heated above 340 K or excited by an ultrafast laser pulse. Due to the strong electron–electron and electron–lattice interactions, modeling the ultrafast IMT in VO2 has proven challenging. Here, we develop an efficient theoretical approach to the light-induced phase transitions by combining a tensor network ansatz for the electrons with a semiclassical description of the nuclei. Our method is based on a quasi-one-dimensional model for the material with the important multiorbital character, electron–lattice coupling, and electron–electron correlations being included. We benchmark our method by showing that it qualitatively captures the ground state phase diagram and finite-temperature phase transitions of VO2. Then, we use the hybrid quantum-classical tensor network approach to simulate the dynamics following photoexcitation. We find that the structure can transform faster than the harmonic phonon modes of the M1 phase, suggesting lattice nonlinearity is key in the SPT. We also find separate timescales in the evolution of dimerization and tilt lattice distortions, as well as the loss and subsequent partial restoration behavior of the displacements, explaining the complex dynamics observed in recent experiments. Moreover, decoupled SPT and IMT dynamics are observed, with the IMT occurs quasi-instantaneously. Our model and approach, which can be extended to a wide range of materials, reveal the unexpected non-monotonic transformation pathways in VO2 and pave the way for future studies of non-thermal phase transformations in quantum materials. |
| 328. | Andriy E. Serebryannikov, Atilla O Cakmak, Evrim Colak Scientific Reports, 15 (1), pp. 7873, 2025, ISSN: 2045-2322. @article{Serebryannikov2025, title = {Effects of gradual deformation of identical and nonidentical, rotated and nonrotated U-shaped subwavelength resonators in few-layer metasurfaces}, author = {Andriy E. Serebryannikov and Atilla O Cakmak and Evrim Colak}, url = {https://doi.org/10.1038/s41598-025-88678-x}, doi = {10.1038/s41598-025-88678-x}, issn = {2045-2322}, year = {2025}, date = {2025-03-06}, journal = {Scientific Reports}, volume = {15}, number = {1}, pages = {7873}, abstract = {Raising of negative-index medium has been going hand-by-hand with the exploration of quasiplanar subwavelength resonators. Now they are widely used in modern microwave, terahertz, and infrared devices, as well as in advanced physics research. Effects of stacking of the arrays of subwavelength resonators in one few-layer metasurface is connected with the key problems of modern electrical engineering, applied physics, and beyond. Recently, the interest to subwavelength resonators has been growing due to the progress in topological photonics and non-Hermitian photonics. In this paper, the selected effects of arrays coupling in a few-layer metasurface are revisited with yet uncommon focus, i.e., survival and (dis)appearance of subwavelength resonances at the gradual deformation of the resonators at a given lattice period. Microwave frequency range has been chosen to illustrate the concept. The case when the metasurfaces comprise two periodically placed U-shaped resonator arrays is considered. The sizes of the resonators are either varied simultaneously for both front-side and back-side arrays or for the back-side array only. The main purpose of this study is to explore the basic scenarios of resonance evolution in the space of geometrical parameters. It is shown that different resonances may be sensitive to the variations in geometrical parameters and to the dissimilarity between the front-side and back-side arrays to a different extent. The obtained results point to the existence of the bands, resonances, polarization-conversion and related asymmetric transmission regimes that are robust to the deformations. They can serve as the starting point in understanding the functional capability of the physical features while adjusting the size for a much wider variety of the types of subwavelength resonators. Their unveiling promises a wide avenue towards the realization of new frequency-domain and angle-domain filters, ultrathin polarization-plane convertors, asymmetric transmission devices and advanced microwave antennas.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Raising of negative-index medium has been going hand-by-hand with the exploration of quasiplanar subwavelength resonators. Now they are widely used in modern microwave, terahertz, and infrared devices, as well as in advanced physics research. Effects of stacking of the arrays of subwavelength resonators in one few-layer metasurface is connected with the key problems of modern electrical engineering, applied physics, and beyond. Recently, the interest to subwavelength resonators has been growing due to the progress in topological photonics and non-Hermitian photonics. In this paper, the selected effects of arrays coupling in a few-layer metasurface are revisited with yet uncommon focus, i.e., survival and (dis)appearance of subwavelength resonances at the gradual deformation of the resonators at a given lattice period. Microwave frequency range has been chosen to illustrate the concept. The case when the metasurfaces comprise two periodically placed U-shaped resonator arrays is considered. The sizes of the resonators are either varied simultaneously for both front-side and back-side arrays or for the back-side array only. The main purpose of this study is to explore the basic scenarios of resonance evolution in the space of geometrical parameters. It is shown that different resonances may be sensitive to the variations in geometrical parameters and to the dissimilarity between the front-side and back-side arrays to a different extent. The obtained results point to the existence of the bands, resonances, polarization-conversion and related asymmetric transmission regimes that are robust to the deformations. They can serve as the starting point in understanding the functional capability of the physical features while adjusting the size for a much wider variety of the types of subwavelength resonators. Their unveiling promises a wide avenue towards the realization of new frequency-domain and angle-domain filters, ultrathin polarization-plane convertors, asymmetric transmission devices and advanced microwave antennas. |
| 327. | Arpan Roy, Arnab Laha, Abhijit Biswas, Bishnu P Pal, Somnath Ghosh, Adam Miranowicz Dynamically encircled higher-order exceptional points in an optical fiber Physica Scripta, 100 (4), pp. 045529, 2025. @article{Roy2025, title = {Dynamically encircled higher-order exceptional points in an optical fiber}, author = {Arpan Roy and Arnab Laha and Abhijit Biswas and Bishnu P Pal and Somnath Ghosh and Adam Miranowicz}, url = {https://dx.doi.org/10.1088/1402-4896/adbea6}, doi = {10.1088/1402-4896/adbea6}, year = {2025}, date = {2025-03-01}, journal = {Physica Scripta}, volume = {100}, number = {4}, pages = {045529}, publisher = {IOP Publishing}, abstract = {The unique properties of exceptional point (EP) singularities, arising from non-Hermitian physics, have unlocked new possibilities for manipulating lightmatter interactions. A tailored gain-loss variation, while encircling higher-order EPs dynamically, can significantly enhance the control of the topological flow of light in multi-level photonic systems. In particular, the integration of dynamically encircled higher-order EPs within fiber geometries holds great promise for advancing specialty optical fiber applications, though a research gap remains in exploring and realizing such configurations. Here, we report a triple-core specialty optical fiber engineered with customized loss and gain to explore the topological characteristics of a third-order EP (EP3), formed by two interconnected second-order EPs (EP2s). We elucidate chiral and nonchiral light transmission through the fiber, based on second- and third-order branch point behaviors and associated adiabatic and nonadiabatic modal characteristics, while considering various dynamical parametric loops to encircle the embedded EPs. We investigate the persistence of EP-induced light dynamics specifically in the parametric regions immediately adjacent to, though not encircling, the embedded EPs, thereby potentially leading to improved device performance. Our findings offer significant implications for the design and implementation of novel light management technologies in all-fiber photonics and communications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The unique properties of exceptional point (EP) singularities, arising from non-Hermitian physics, have unlocked new possibilities for manipulating lightmatter interactions. A tailored gain-loss variation, while encircling higher-order EPs dynamically, can significantly enhance the control of the topological flow of light in multi-level photonic systems. In particular, the integration of dynamically encircled higher-order EPs within fiber geometries holds great promise for advancing specialty optical fiber applications, though a research gap remains in exploring and realizing such configurations. Here, we report a triple-core specialty optical fiber engineered with customized loss and gain to explore the topological characteristics of a third-order EP (EP3), formed by two interconnected second-order EPs (EP2s). We elucidate chiral and nonchiral light transmission through the fiber, based on second- and third-order branch point behaviors and associated adiabatic and nonadiabatic modal characteristics, while considering various dynamical parametric loops to encircle the embedded EPs. We investigate the persistence of EP-induced light dynamics specifically in the parametric regions immediately adjacent to, though not encircling, the embedded EPs, thereby potentially leading to improved device performance. Our findings offer significant implications for the design and implementation of novel light management technologies in all-fiber photonics and communications. |
| 326. | Syamlal Sankaran Kunnath, Mateusz Zelent, Mathieu Moalic, Maciej Krawczyk Small Structures, n/a (n/a), pp. 2400627, 2025. @article{https://doi.org/10.1002/sstr.202400627, title = {Enhancement of Dynamical Coupling in Artificial Spin-Ice Systems by Incorporating Perpendicularly Magnetized Ferromagnetic Matrix}, author = {Syamlal Sankaran Kunnath and Mateusz Zelent and Mathieu Moalic and Maciej Krawczyk}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/sstr.202400627}, doi = {https://doi.org/10.1002/sstr.202400627}, year = {2025}, date = {2025-02-19}, journal = {Small Structures}, volume = {n/a}, number = {n/a}, pages = {2400627}, abstract = {Artificial spin-ice (ASI) systems, consisting of arrays of interacting ferromagnetic nanoelements, offer a versatile platform for reconfigurable magnonics with potential in GHz logic and neuromorphic computing. However, weak dipolar coupling between nanoelements severely limits their functionality. A rich spin-wave spectrum is numerically demonstrated in an ASI structure immersed in a perpendicularly magnetized ferromagnetic matrix, which is different from a conventional ASI system. A strong magnon–magnon coupling is observed between the bulk second-order mode of the ASI and the fundamental mode of the matrix, supported by a pronounced anticrossing frequency gap. It is shown that, in addition to the internanoelement dipolar coupling, exchange interactions at the nanoelement-matrix interface play a crucial role in this hybridization. Furthermore, the strength of the coupling can be enhanced by almost 40% just by reconfiguring the magnetization at the vertices from low-energy to high-energy monopole states. These results open the way to exploit ASI systems for magnonic applications, taking advantage of the strong coupling and vertex-dependent dynamics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Artificial spin-ice (ASI) systems, consisting of arrays of interacting ferromagnetic nanoelements, offer a versatile platform for reconfigurable magnonics with potential in GHz logic and neuromorphic computing. However, weak dipolar coupling between nanoelements severely limits their functionality. A rich spin-wave spectrum is numerically demonstrated in an ASI structure immersed in a perpendicularly magnetized ferromagnetic matrix, which is different from a conventional ASI system. A strong magnon–magnon coupling is observed between the bulk second-order mode of the ASI and the fundamental mode of the matrix, supported by a pronounced anticrossing frequency gap. It is shown that, in addition to the internanoelement dipolar coupling, exchange interactions at the nanoelement-matrix interface play a crucial role in this hybridization. Furthermore, the strength of the coupling can be enhanced by almost 40% just by reconfiguring the magnetization at the vertices from low-energy to high-energy monopole states. These results open the way to exploit ASI systems for magnonic applications, taking advantage of the strong coupling and vertex-dependent dynamics. |
| 325. | D. Mosić, O. M. Baksalary Solvability of certain systems of matrix equations related to the Penrose equations Linear and Multilinear Algebra, 73 (10), pp. 2428-2449, 2025. @article{Mosić2025, title = {Solvability of certain systems of matrix equations related to the Penrose equations}, author = {D. Mosić and O. M. Baksalary }, doi = {10.1080/03081087.2025.2464653}, year = {2025}, date = {2025-02-16}, journal = {Linear and Multilinear Algebra}, volume = {73}, number = {10}, pages = {2428-2449}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 324. | Krzysztof Sobucki, Igor Lyubchanskii, Maciej Krawczyk, Paweł Gruszecki Goos-Hänchen shift of inelastically scattered spin-wave beams and cascade nonlinear magnon processes Scientific Reports, 15 (1), pp. 5538, 2025, ISSN: 2045-2322. @article{Sobucki2025, title = {Goos-Hänchen shift of inelastically scattered spin-wave beams and cascade nonlinear magnon processes}, author = {Krzysztof Sobucki and Igor Lyubchanskii and Maciej Krawczyk and Paweł Gruszecki}, url = {https://doi.org/10.1038/s41598-025-86879-y}, doi = {10.1038/s41598-025-86879-y}, issn = {2045-2322}, year = {2025}, date = {2025-02-14}, journal = {Scientific Reports}, volume = {15}, number = {1}, pages = {5538}, abstract = {We study, using micromagnetic simulations, the inelastic scattering of spin-wave beams on edge-localized spin-wave modes in a thin ferromagnetic film. In the splitting and confluence processes, the new spin-wave beams are generated with frequencies shifted by the edge-mode frequency. We report that inelastically scattered spin-wave beams in both processes not only change their direction of propagation but also undergo lateral shifts along the interface, analogous to the Goos--Hänchen effect known in optics. These shifts of inelastically scattered beams, for a few special cases described in the paper, can be in the range of several wavelengths, which is larger than the Goos--Hänchen shift of elastically reflected beam. Unexpectedly, at selected frequencies, we found a significant increase in the value of the lateral shifts of the scattered spin-wave beams formed in the confluence process. We show that this effect is associated with the cascading nonlinear processes taking place at the edge of the film and involving the primary edge spin wave. Our results make an important contribution to the understanding of the nonlinear nature of spin waves and provide a way to exploit it in signal processing with magnons.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study, using micromagnetic simulations, the inelastic scattering of spin-wave beams on edge-localized spin-wave modes in a thin ferromagnetic film. In the splitting and confluence processes, the new spin-wave beams are generated with frequencies shifted by the edge-mode frequency. We report that inelastically scattered spin-wave beams in both processes not only change their direction of propagation but also undergo lateral shifts along the interface, analogous to the Goos--Hänchen effect known in optics. These shifts of inelastically scattered beams, for a few special cases described in the paper, can be in the range of several wavelengths, which is larger than the Goos--Hänchen shift of elastically reflected beam. Unexpectedly, at selected frequencies, we found a significant increase in the value of the lateral shifts of the scattered spin-wave beams formed in the confluence process. We show that this effect is associated with the cascading nonlinear processes taking place at the edge of the film and involving the primary edge spin wave. Our results make an important contribution to the understanding of the nonlinear nature of spin waves and provide a way to exploit it in signal processing with magnons. |
| 323. | C. Jasiukiewicz, A. Sinner, I. Weymann, T. Domański, L. Chotorlishvili Phys. Rev. B, 111 , pp. 075415, 2025. @article{Jasiukiewicz2025, title = {Entanglement between quantum dots transmitted via a Majorana wire: Insights from the fermionic negativity, concurrence, and quantum mutual information}, author = {C. Jasiukiewicz and A. Sinner and I. Weymann and T. Domański and L. Chotorlishvili }, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.111.075415}, doi = {10.1103/PhysRevB.111.075415}, year = {2025}, date = {2025-02-12}, journal = {Phys. Rev. B}, volume = {111}, pages = {075415}, abstract = {We study quantum entanglement in a system comprising two quantum dots interconnected through the short topological superconducting nanowire, which hosts overlapping boundary Majorana modes. Inspecting the fermionic negativity, we analyze the variation of entanglement against the position of the energy levels of quantum dots and their hybridization with the topological superconducting nanowire. In the absence of electron correlations, the optimal entanglement occurs when the energy levels coincide with the zero-energy Majorana modes, whereas upon increasing the hybridizations, the entanglement is gradually suppressed. Such monotonous behavior is no longer valid when the quantum dot levels are detuned from the zero-energy. Under these circumstances, the quantum dots become maximally entangled for a certain optimal hybridization. Moreover, we study the thermal concurrence to explore the entanglement properties at finite temperatures. We also compute the quantum mutual information and propose recipes for robust finite-temperature entanglement transmission via Majorana modes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study quantum entanglement in a system comprising two quantum dots interconnected through the short topological superconducting nanowire, which hosts overlapping boundary Majorana modes. Inspecting the fermionic negativity, we analyze the variation of entanglement against the position of the energy levels of quantum dots and their hybridization with the topological superconducting nanowire. In the absence of electron correlations, the optimal entanglement occurs when the energy levels coincide with the zero-energy Majorana modes, whereas upon increasing the hybridizations, the entanglement is gradually suppressed. Such monotonous behavior is no longer valid when the quantum dot levels are detuned from the zero-energy. Under these circumstances, the quantum dots become maximally entangled for a certain optimal hybridization. Moreover, we study the thermal concurrence to explore the entanglement properties at finite temperatures. We also compute the quantum mutual information and propose recipes for robust finite-temperature entanglement transmission via Majorana modes. |
| 322. | Sylwia Kudła, Vitalii K. Dugaev, Józef Barnaś, Anna Dyrdał Longitudinal magnetoresistance in graphene with random Rashba spin-orbit interaction Phys. Rev. B, 111 , pp. 075413, 2025. @article{Kudla2025, title = {Longitudinal magnetoresistance in graphene with random Rashba spin-orbit interaction}, author = {Sylwia Kudła and Vitalii K. Dugaev and Józef Barnaś and Anna Dyrdał}, url = {https://link.aps.org/doi/10.1103/PhysRevB.111.075413}, doi = {10.1103/PhysRevB.111.075413}, year = {2025}, date = {2025-02-11}, journal = {Phys. Rev. B}, volume = {111}, pages = {075413}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
| 321. | Piotr Trocha Scientific Reports, 15 (4904), 2025. @article{Trocha2025, title = {Spin-dependent thermoelectric properties of a hybrid ferromagnetic metal/quantum dot/topological insulator junction}, author = {Piotr Trocha}, url = {https://www.nature.com/articles/s41598-025-87931-7}, doi = {10.1038/s41598-025-87931-7}, year = {2025}, date = {2025-02-10}, journal = {Scientific Reports}, volume = {15}, number = {4904}, abstract = {The thermoelectric properties of hybrid system based on a single-level quantum dot coupled to a ferromagnetic metallic lead and attached to the surface states of a three-dimensional topological insulator are theoretically investigated. On the surface of a three-dimensional topological insulator, massless helical Dirac fermions emerge. We calculate the thermoelectric coefficients, including electrical conductance, Seebeck coefficient (thermopower), heat conductance, and the figure of merit, using the nonequilibrium Green’s function technique. The results are analyzed in terms of the emergence of new effects. The calculations are performed within the Hubbard I approximation concerning the dot’s Coulomb interactions. Additionally, the spin-dependent coupling of the quantum dot to the ferromagnetic lead lifts the spin degeneracy of the dot’s level, which influences the transport properties of the system. We incorporate this effect perturbatively to obtain the spin-dependent renormalization of the dot’s level. We also consider the case of finite spin accumulation in the ferromagnetic electrode, which leads to spin thermoelectric effects.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The thermoelectric properties of hybrid system based on a single-level quantum dot coupled to a ferromagnetic metallic lead and attached to the surface states of a three-dimensional topological insulator are theoretically investigated. On the surface of a three-dimensional topological insulator, massless helical Dirac fermions emerge. We calculate the thermoelectric coefficients, including electrical conductance, Seebeck coefficient (thermopower), heat conductance, and the figure of merit, using the nonequilibrium Green’s function technique. The results are analyzed in terms of the emergence of new effects. The calculations are performed within the Hubbard I approximation concerning the dot’s Coulomb interactions. Additionally, the spin-dependent coupling of the quantum dot to the ferromagnetic lead lifts the spin degeneracy of the dot’s level, which influences the transport properties of the system. We incorporate this effect perturbatively to obtain the spin-dependent renormalization of the dot’s level. We also consider the case of finite spin accumulation in the ferromagnetic electrode, which leads to spin thermoelectric effects. |
| 320. | Emil Siuda, Piotr Trocha Thermal Gradient Powering Spin Current in Quantum Dot-Magnetic Insulators Hybrid Journal of Superconductivity and Novel Magnetism, 38 (81), 2025. @article{Siuda2025, title = {Thermal Gradient Powering Spin Current in Quantum Dot-Magnetic Insulators Hybrid}, author = {Emil Siuda and Piotr Trocha }, url = {https://link.springer.com/article/10.1007/s10948-025-06921-y}, doi = {10.1007/s10948-025-06921-y}, year = {2025}, date = {2025-02-07}, journal = {Journal of Superconductivity and Novel Magnetism}, volume = {38}, number = {81}, abstract = {The growing energy consumption of the computational sector worldwide necessitates the search for sustainable methods of powering and performing calculations. The fast-emerging field of spin caloritronics offers a promising solution by combining the advantages of performing computations on spins instead of charges and driving these computations through temperature differences rather than voltage. Among the various approaches, spin waves and their quanta of excitations, known as magnons, are considered promising carriers of spin-encoded information. In this article, we examine the magnon current generated in a system composed of a magnetic insulator/quantum dot/magnetic insulator, driven by a small temperature difference applied between the two insulators. By expanding the magnon current in terms of the applied temperature bias, we analyze the contributions of successive terms up to the third order of the temperature difference. Each term exhibits a similar structure, consisting of a driving-like and a damping-like component. The driving-like term is dependent on the coupling strength between the quantum dot and the electrodes. We explicitly show that the second-order term of the magnon current vanishes when the couplings of the quantum dot to the magnetic insulators are equal. Overall, the first two terms are sufficient to capture the behavior of the magnon current across the full range of temperature differences. For extreme values of the temperature gradient, the approximate results align with the exact ones only when there is significant asymmetry in the coupling strengths. Finally, we demonstrate that the system can function as a spin diode, capable of rectifying the magnon current when the temperature bias is reversed.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The growing energy consumption of the computational sector worldwide necessitates the search for sustainable methods of powering and performing calculations. The fast-emerging field of spin caloritronics offers a promising solution by combining the advantages of performing computations on spins instead of charges and driving these computations through temperature differences rather than voltage. Among the various approaches, spin waves and their quanta of excitations, known as magnons, are considered promising carriers of spin-encoded information. In this article, we examine the magnon current generated in a system composed of a magnetic insulator/quantum dot/magnetic insulator, driven by a small temperature difference applied between the two insulators. By expanding the magnon current in terms of the applied temperature bias, we analyze the contributions of successive terms up to the third order of the temperature difference. Each term exhibits a similar structure, consisting of a driving-like and a damping-like component. The driving-like term is dependent on the coupling strength between the quantum dot and the electrodes. We explicitly show that the second-order term of the magnon current vanishes when the couplings of the quantum dot to the magnetic insulators are equal. Overall, the first two terms are sufficient to capture the behavior of the magnon current across the full range of temperature differences. For extreme values of the temperature gradient, the approximate results align with the exact ones only when there is significant asymmetry in the coupling strengths. Finally, we demonstrate that the system can function as a spin diode, capable of rectifying the magnon current when the temperature bias is reversed. |
| 319. | Jhen-Dong Lin, Po-Chen Kuo, Neill Lambert, Adam Miranowicz, Franco Nori, Yueh-Nan Chen Non-Markovian quantum exceptional points Nature Communications, 16 (1), pp. 1289, 2025, ISSN: 2041-1723. @article{Lin2025, title = {Non-Markovian quantum exceptional points}, author = {Jhen-Dong Lin and Po-Chen Kuo and Neill Lambert and Adam Miranowicz and Franco Nori and Yueh-Nan Chen}, url = {https://doi.org/10.1038/s41467-025-56242-w}, doi = {10.1038/s41467-025-56242-w}, issn = {2041-1723}, year = {2025}, date = {2025-02-03}, journal = {Nature Communications}, volume = {16}, number = {1}, pages = {1289}, abstract = {Exceptional points (EPs) are singularities in the spectra of non-Hermitian operators where eigenvalues and eigenvectors coalesce. Open quantum systems have recently been explored as EP testbeds due to their non-Hermitian nature. However, most studies focus on the Markovian limit, leaving a gap in understanding EPs in the non-Markovian regime. This work addresses this gap by proposing a general framework based on two numerically exact descriptions of non-Markovian dynamics: the pseudomode equation of motion (PMEOM) and the hierarchical equations of motion (HEOM). The PMEOM is particularly useful due to its Lindblad-type structure, aligning with previous studies in the Markovian regime while offering deeper insights into EP identification. This framework incorporates non-Markovian effects through auxiliary degrees of freedom, enabling the discovery of additional or higher-order EPs that are inaccessible in the Markovian regime. We demonstrate the utility of this approach using the spin-boson model and linear bosonic systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Exceptional points (EPs) are singularities in the spectra of non-Hermitian operators where eigenvalues and eigenvectors coalesce. Open quantum systems have recently been explored as EP testbeds due to their non-Hermitian nature. However, most studies focus on the Markovian limit, leaving a gap in understanding EPs in the non-Markovian regime. This work addresses this gap by proposing a general framework based on two numerically exact descriptions of non-Markovian dynamics: the pseudomode equation of motion (PMEOM) and the hierarchical equations of motion (HEOM). The PMEOM is particularly useful due to its Lindblad-type structure, aligning with previous studies in the Markovian regime while offering deeper insights into EP identification. This framework incorporates non-Markovian effects through auxiliary degrees of freedom, enabling the discovery of additional or higher-order EPs that are inaccessible in the Markovian regime. We demonstrate the utility of this approach using the spin-boson model and linear bosonic systems. |
| 318. | Gianluca Gubbiotti, Anjan Barman, Sam Ladak, Cristina Bran, Dirk Grundler, Michael Huth, Harald Plank, Georg Schmidt, Sebastiaan van Dijken, Robert Streubel, Oleksandr Dobrovoloskiy, Valerio Scagnoli, Laura Heyderman, Claire Donnelly, Olav Hellwig, Lorenzo Fallarino, Benjamin M Jungfleisch, Alan Farhan, Nicolò Maccaferri, Paolo Vavassori, Peter Fischer, Riccardo Tomasello, Giovanni Finocchio, Rodolphe Clérac, Roberta Sessoli, Denys Makarov, Denis D Sheka, Maciej Krawczyk, Rodolfo Gallardo, Pedro Landeros, Massimiliano d’Aquino, Riccardo Hertel, Philipp Pirro, Florin Ciubotaru, Markus Becherer, Jack Gartside, Teruo Ono, Paolo Bortolotti, Amalio Fernández-Pacheco 2025 roadmap on 3D nanomagnetism Journal of Physics: Condensed Matter, 37 (14), pp. 143502, 2025. @article{Gubbiotti_2025, title = {2025 roadmap on 3D nanomagnetism}, author = {Gianluca Gubbiotti and Anjan Barman and Sam Ladak and Cristina Bran and Dirk Grundler and Michael Huth and Harald Plank and Georg Schmidt and Sebastiaan van Dijken and Robert Streubel and Oleksandr Dobrovoloskiy and Valerio Scagnoli and Laura Heyderman and Claire Donnelly and Olav Hellwig and Lorenzo Fallarino and Benjamin M Jungfleisch and Alan Farhan and Nicolò Maccaferri and Paolo Vavassori and Peter Fischer and Riccardo Tomasello and Giovanni Finocchio and Rodolphe Clérac and Roberta Sessoli and Denys Makarov and Denis D Sheka and Maciej Krawczyk and Rodolfo Gallardo and Pedro Landeros and Massimiliano d’Aquino and Riccardo Hertel and Philipp Pirro and Florin Ciubotaru and Markus Becherer and Jack Gartside and Teruo Ono and Paolo Bortolotti and Amalio Fernández-Pacheco}, url = {https://dx.doi.org/10.1088/1361-648X/ad9655}, doi = {10.1088/1361-648X/ad9655}, year = {2025}, date = {2025-02-01}, journal = {Journal of Physics: Condensed Matter}, volume = {37}, number = {14}, pages = {143502}, publisher = {IOP Publishing}, abstract = {The transition from planar to three-dimensional (3D) magnetic nanostructures represents a significant advancement in both fundamental research and practical applications, offering vast potential for next-generation technologies like ultrahigh-density storage, memory, logic, and neuromorphic computing. Despite being a relatively new field, the emergence of 3D nanomagnetism presents numerous opportunities for innovation, prompting the creation of a comprehensive roadmap by leading international researchers. This roadmap aims to facilitate collaboration and interdisciplinary dialogue to address challenges in materials science, physics, engineering, and computing. The roadmap comprises eighteen sections, roughly divided into three blocks. The first block explores the fundamentals of 3D nanomagnetism, focusing on recent trends in fabrication techniques and imaging methods crucial for understanding complex spin textures, curved surfaces, and small-scale interactions. Techniques such as two-photon lithography and focused electron beam-induced deposition enable the creation of intricate 3D architectures, while advanced imaging methods like electron holography and synchrotron x-ray tomography provide nanoscale spatial resolution for studying magnetization dynamics in three dimensions. Various 3D magnetic systems, including coupled multilayer systems, artificial spin-ice, magneto-plasmonic systems, topological spin textures, and molecular magnets are discussed. The second block introduces analytical and numerical methods for investigating 3D nanomagnetic structures and curvilinear systems, highlighting geometrically curved architectures, interconnected nanowire systems, and other complex geometries. Finite element methods are emphasized for capturing complex geometries, along with direct frequency domain solutions for addressing magnonic problems. The final block focuses on 3D magnonic crystals and networks, exploring their fundamental properties and potential applications in magnonic circuits, memory, and spintronics. Computational approaches using 3D nanomagnetic systems and complex topological textures in 3D spintronics are highlighted for their potential to enable faster and more energy-efficient computing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The transition from planar to three-dimensional (3D) magnetic nanostructures represents a significant advancement in both fundamental research and practical applications, offering vast potential for next-generation technologies like ultrahigh-density storage, memory, logic, and neuromorphic computing. Despite being a relatively new field, the emergence of 3D nanomagnetism presents numerous opportunities for innovation, prompting the creation of a comprehensive roadmap by leading international researchers. This roadmap aims to facilitate collaboration and interdisciplinary dialogue to address challenges in materials science, physics, engineering, and computing. The roadmap comprises eighteen sections, roughly divided into three blocks. The first block explores the fundamentals of 3D nanomagnetism, focusing on recent trends in fabrication techniques and imaging methods crucial for understanding complex spin textures, curved surfaces, and small-scale interactions. Techniques such as two-photon lithography and focused electron beam-induced deposition enable the creation of intricate 3D architectures, while advanced imaging methods like electron holography and synchrotron x-ray tomography provide nanoscale spatial resolution for studying magnetization dynamics in three dimensions. Various 3D magnetic systems, including coupled multilayer systems, artificial spin-ice, magneto-plasmonic systems, topological spin textures, and molecular magnets are discussed. The second block introduces analytical and numerical methods for investigating 3D nanomagnetic structures and curvilinear systems, highlighting geometrically curved architectures, interconnected nanowire systems, and other complex geometries. Finite element methods are emphasized for capturing complex geometries, along with direct frequency domain solutions for addressing magnonic problems. The final block focuses on 3D magnonic crystals and networks, exploring their fundamental properties and potential applications in magnonic circuits, memory, and spintronics. Computational approaches using 3D nanomagnetic systems and complex topological textures in 3D spintronics are highlighted for their potential to enable faster and more energy-efficient computing. |
| 317. | Anand Manaparambil, Andreas Weichselbaum, Jan von Delft, Ireneusz Weymann Nonequilibrium steady-state thermoelectrics of Kondo-correlated quantum dots Phys. Rev. B, 111 , pp. 035445, 2025. @article{Manaparambil2025, title = {Nonequilibrium steady-state thermoelectrics of Kondo-correlated quantum dots}, author = {Anand Manaparambil and Andreas Weichselbaum and Jan von Delft and Ireneusz Weymann}, url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.111.035445}, doi = {10.1103/PhysRevB.111.035445}, year = {2025}, date = {2025-01-27}, journal = {Phys. Rev. B}, volume = {111}, pages = {035445}, abstract = {The transport across a Kondo-correlated quantum dot coupled to two leads with independent temperatures and chemical potentials is studied using a controlled nonperturbative, and in this sense numerically exact, treatment based on a hybrid numerical renormalization group combined with time-dependent density matrix renormalization group (NRG-tDMRG). In the Kondo regime, for sufficiently large fixed voltage bias 𝑉≳𝑇𝐾, with 𝑇𝐾 the Kondo temperature, we find a peak in the conductance vs the temperature gradient Δ𝑇=𝑇𝑅−𝑇𝐿 across left and right lead. Focusing then on zero voltage bias but finite Δ𝑇 far beyond linear response, we reveal the dependence of the characteristic zero-bias conductance on the individual lead temperatures. We find that the finite-Δ𝑇 data behaves quantitatively similar to linear response with an effective equilibrium temperature derived from the different lead temperatures. The regime of sign changes in the Seebeck coefficient, signaling the presence of Kondo correlations, and its dependence on the individual lead temperatures provide a complete picture of the Kondo regime in the presence of finite-temperature gradients. The results from the zero-bias conductance and Seebeck coefficient studies unveil an approximate “Kondo circle” in the 𝑇𝐿/𝑇𝑅 plane as the regime within which the Kondo correlations dominate. We also study the heat current and the corresponding heat conductance vs finite Δ𝑇. We provide a polynomial fit for our numerical results for the thermocurrent as a function of the individual lead temperatures, which may be used to fit experimental data in the Kondo regime.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The transport across a Kondo-correlated quantum dot coupled to two leads with independent temperatures and chemical potentials is studied using a controlled nonperturbative, and in this sense numerically exact, treatment based on a hybrid numerical renormalization group combined with time-dependent density matrix renormalization group (NRG-tDMRG). In the Kondo regime, for sufficiently large fixed voltage bias 𝑉≳𝑇𝐾, with 𝑇𝐾 the Kondo temperature, we find a peak in the conductance vs the temperature gradient Δ𝑇=𝑇𝑅−𝑇𝐿 across left and right lead. Focusing then on zero voltage bias but finite Δ𝑇 far beyond linear response, we reveal the dependence of the characteristic zero-bias conductance on the individual lead temperatures. We find that the finite-Δ𝑇 data behaves quantitatively similar to linear response with an effective equilibrium temperature derived from the different lead temperatures. The regime of sign changes in the Seebeck coefficient, signaling the presence of Kondo correlations, and its dependence on the individual lead temperatures provide a complete picture of the Kondo regime in the presence of finite-temperature gradients. The results from the zero-bias conductance and Seebeck coefficient studies unveil an approximate “Kondo circle” in the 𝑇𝐿/𝑇𝑅 plane as the regime within which the Kondo correlations dominate. We also study the heat current and the corresponding heat conductance vs finite Δ𝑇. We provide a polynomial fit for our numerical results for the thermocurrent as a function of the individual lead temperatures, which may be used to fit experimental data in the Kondo regime. |
| 316. | Piotr Trocha, Thibaut Jonckheere, Jérôme Rech, Thierry Martin Thermoelectric properties of a quantum dot attached to normal metal and topological superconductor Scientific Reports, 15 (3068), 2025. @article{Trocha2025b, title = {Thermoelectric properties of a quantum dot attached to normal metal and topological superconductor}, author = {Piotr Trocha and Thibaut Jonckheere and Jérôme Rech and Thierry Martin}, url = {https://www.nature.com/articles/s41598-024-84770-w}, doi = {10.1038/s41598-024-84770-w}, year = {2025}, date = {2025-01-24}, journal = {Scientific Reports}, volume = {15}, number = {3068}, abstract = {The thermoelectric properties of hybrid systems based on a single-level quantum dot coupled to a normal-metal/half-metallic lead and attached to a topological superconductor wire are investigated. The topological superconductor wire is modeled by a spinless p-wave superconductor which hosts both a Majorana bound state at its extremity and above gap quasiparticle excitations. The main interest of our investigation is to study the interplay of sub-gap and single-particle tunneling processes and their contributions to the thermoelectric response of the considered system. The above gap tunneling driven by a temperature gradient is responsible for relatively large thermopower, whereas sub-gap processes only indirectly influence the thermoelectric response. The thermoelectric coefficients, including electric conductance, Seebeck coefficient (thermopower), heat conductance, and figure of merit, are calculated by means of the non-equilibrium Green’s function technique and the temperature dependence of the superconducting gap is considered within the BCS theory. We also consider the system out of equilibrium working as a heat engine. The output power and the corresponding efficiency are presented. Interestingly, under certain conditions, it is possible to extract more power in the superconducting phase than in the normal phase, with comparable efficiency.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The thermoelectric properties of hybrid systems based on a single-level quantum dot coupled to a normal-metal/half-metallic lead and attached to a topological superconductor wire are investigated. The topological superconductor wire is modeled by a spinless p-wave superconductor which hosts both a Majorana bound state at its extremity and above gap quasiparticle excitations. The main interest of our investigation is to study the interplay of sub-gap and single-particle tunneling processes and their contributions to the thermoelectric response of the considered system. The above gap tunneling driven by a temperature gradient is responsible for relatively large thermopower, whereas sub-gap processes only indirectly influence the thermoelectric response. The thermoelectric coefficients, including electric conductance, Seebeck coefficient (thermopower), heat conductance, and figure of merit, are calculated by means of the non-equilibrium Green’s function technique and the temperature dependence of the superconducting gap is considered within the BCS theory. We also consider the system out of equilibrium working as a heat engine. The output power and the corresponding efficiency are presented. Interestingly, under certain conditions, it is possible to extract more power in the superconducting phase than in the normal phase, with comparable efficiency. |
| 315. | Mateusz Gołębiewski, Krzysztof Szulc, Maciej Krawczyk Magnetic field controlled surface localization of ferromagnetic resonance modes in 3D nanostructures Acta Materialia, 283 , pp. 120499, 2025, ISSN: 1359-6454. @article{GOLEBIEWSKI2025120499, title = {Magnetic field controlled surface localization of ferromagnetic resonance modes in 3D nanostructures}, author = {Mateusz Gołębiewski and Krzysztof Szulc and Maciej Krawczyk}, url = {https://www.sciencedirect.com/science/article/pii/S1359645424008486}, doi = {https://doi.org/10.1016/j.actamat.2024.120499}, issn = {1359-6454}, year = {2025}, date = {2025-01-15}, journal = {Acta Materialia}, volume = {283}, pages = {120499}, abstract = {By extending the current understanding and use of magnonics beyond conventional planar systems, we demonstrate the surface localization of ferromagnetic resonance (FMR) modes through the design of complex three-dimensional nanostructures. Using micromagnetic simulations, we systematically investigate woodpile-like scaffolds and gyroids — periodic chiral entities characterized by their triple junctions. The study highlights the critical role of demagnetizing fields and exchange energy in determining the FMR responses of 3D nanosystems, especially the strongly asymmetric distribution of the spin-wave mode over the system’s height. Importantly, the top–bottom dynamic switching of the surface mode localization across the structures in response to changes in magnetic field orientation provides a new method for controlling magnetization dynamics. The results demonstrate the critical role of the geometric features in dictating the dynamic magnetic behavior of three-dimensional nanostructures, paving the way for both experimental exploration and practical advances in 3D magnonics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } By extending the current understanding and use of magnonics beyond conventional planar systems, we demonstrate the surface localization of ferromagnetic resonance (FMR) modes through the design of complex three-dimensional nanostructures. Using micromagnetic simulations, we systematically investigate woodpile-like scaffolds and gyroids — periodic chiral entities characterized by their triple junctions. The study highlights the critical role of demagnetizing fields and exchange energy in determining the FMR responses of 3D nanosystems, especially the strongly asymmetric distribution of the spin-wave mode over the system’s height. Importantly, the top–bottom dynamic switching of the surface mode localization across the structures in response to changes in magnetic field orientation provides a new method for controlling magnetization dynamics. The results demonstrate the critical role of the geometric features in dictating the dynamic magnetic behavior of three-dimensional nanostructures, paving the way for both experimental exploration and practical advances in 3D magnonics. |
| 314. | Jacek Baranowski, Bogusław Mróz, Sławomir Mielcarek, I Iatsunskyi, Aleksandra Trzaskowska Scientific Reports, 15 (1), pp. 1358, 2025, ISSN: 2045-2322. @article{Baranowski2025, title = {High resolution Brillouin spectroscopy of the surface acoustic waves in Sb2Te3 van der Waals single crystals}, author = {Jacek Baranowski and Bogusław Mróz and Sławomir Mielcarek and I Iatsunskyi and Aleksandra Trzaskowska}, url = {https://doi.org/10.1038/s41598-025-85742-4}, doi = {10.1038/s41598-025-85742-4}, issn = {2045-2322}, year = {2025}, date = {2025-01-08}, journal = {Scientific Reports}, volume = {15}, number = {1}, pages = {1358}, abstract = {High-resolution Brillouin spectroscopy was employed to investigate the anisotropy in surface wave velocities within a bulk single crystal of Sb2Te3, a well-known layered van der Waals material. By leveraging the bulk elastic constants derived from various simulation methods, we were able to theoretically calculate the distribution of surface acoustic phonon velocities on the cleavage plane of the material. Upon analyzing multiple simulation results, it became evident that the most significant discrepancies arose in the calculations of the elastic constant c33, with values ranging from 48 to 98 GPa. Consequently, a direct measurement of the c33 elastic constant for Sb2Te3 was attempted. Through our ellipsometry results, we determined both the real and imaginary components of the refractive index, leading to an experimental determination of the c33 elastic constant, which was found to be 47.9 GPa. Additionally the results of the conducted studies enabled the analytical determination of all components of the elastic property tensor of the investigated material.}, keywords = {}, pubstate = {published}, tppubtype = {article} } High-resolution Brillouin spectroscopy was employed to investigate the anisotropy in surface wave velocities within a bulk single crystal of Sb2Te3, a well-known layered van der Waals material. By leveraging the bulk elastic constants derived from various simulation methods, we were able to theoretically calculate the distribution of surface acoustic phonon velocities on the cleavage plane of the material. Upon analyzing multiple simulation results, it became evident that the most significant discrepancies arose in the calculations of the elastic constant c33, with values ranging from 48 to 98 GPa. Consequently, a direct measurement of the c33 elastic constant for Sb2Te3 was attempted. Through our ellipsometry results, we determined both the real and imaginary components of the refractive index, leading to an experimental determination of the c33 elastic constant, which was found to be 47.9 GPa. Additionally the results of the conducted studies enabled the analytical determination of all components of the elastic property tensor of the investigated material. |
| 313. | Krzysztof Szulc, Mateusz Zelent, Maciej Krawczyk APL Materials, 13 (9), pp. 091108, 2025, ISSN: 2166-532X. @article{10.1063/5.0277362, title = {Multifunctional magnonic platform based on the interplay between spin-wave waveguide and nanodots with PMA and DMI}, author = {Krzysztof Szulc and Mateusz Zelent and Maciej Krawczyk}, url = {https://doi.org/10.1063/5.0277362}, doi = {10.1063/5.0277362}, issn = {2166-532X}, year = {2025}, date = {2025-01-01}, journal = {APL Materials}, volume = {13}, number = {9}, pages = {091108}, abstract = {Materials with perpendicular magnetic anisotropy (PMA) and antisymmetric exchange interactions are widely explored in spintronics but are of limited use in magnonics due to high damping. We present a hybrid magnonic crystal composed of a chain of circular nanodots with strong PMA and Dzyaloshinskii–Moriya interaction (DMI), positioned above a spin-wave waveguide made of permalloy. Due to the dipolar coupling between the subsystems, a strongly bound hybrid magnetization texture is formed, with two stable magnetization states in the nanodots: a single-domain state and an egg-shaped skyrmion state, allowing reprogramming of the system properties. Numerical results show complex spin-wave spectra with several key features for magnonics: programmable Bragg and non-Bragg bandgaps correlated with magnon–magnon couplings, the flat bands and bound states for the skyrmion state, and exclusively waveguide-dominated modes for the single-domain state. With these properties, the proposed hybrid magnonic crystal has different functionalities that overcome the damping limitations of materials with PMA and DMI and open up potential applications in spin-wave filtering, spin-wave generation, quantum magnonics, and analog magnonics, in particular in the realization of magnonic neural networks.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Materials with perpendicular magnetic anisotropy (PMA) and antisymmetric exchange interactions are widely explored in spintronics but are of limited use in magnonics due to high damping. We present a hybrid magnonic crystal composed of a chain of circular nanodots with strong PMA and Dzyaloshinskii–Moriya interaction (DMI), positioned above a spin-wave waveguide made of permalloy. Due to the dipolar coupling between the subsystems, a strongly bound hybrid magnetization texture is formed, with two stable magnetization states in the nanodots: a single-domain state and an egg-shaped skyrmion state, allowing reprogramming of the system properties. Numerical results show complex spin-wave spectra with several key features for magnonics: programmable Bragg and non-Bragg bandgaps correlated with magnon–magnon couplings, the flat bands and bound states for the skyrmion state, and exclusively waveguide-dominated modes for the single-domain state. With these properties, the proposed hybrid magnonic crystal has different functionalities that overcome the damping limitations of materials with PMA and DMI and open up potential applications in spin-wave filtering, spin-wave generation, quantum magnonics, and analog magnonics, in particular in the realization of magnonic neural networks. |
| 312. | Piotr Graczyk, Bivas Rana, Aleksandra Trzaskowska, B K Mahato, Jarosław W. Kłos, Maciej Krawczyk, A Barman Ultrasonics, 148 , pp. 107522, 2025, ISSN: 0041-624X. @article{GRACZYK2025107522b, title = {Optical excitation and detection of high-frequency Sezawa modes in Si/SiO2 system decorated with Ni80Fe20 nanodot arrays}, author = {Piotr Graczyk and Bivas Rana and Aleksandra Trzaskowska and B K Mahato and Jarosław W. Kłos and Maciej Krawczyk and A Barman}, url = {https://www.sciencedirect.com/science/article/pii/S0041624X24002853}, doi = {https://doi.org/10.1016/j.ultras.2024.107522}, issn = {0041-624X}, year = {2025}, date = {2025-01-01}, journal = {Ultrasonics}, volume = {148}, pages = {107522}, abstract = {Surface acoustic waves have emerged as one of the potential candidates for the development of next-generation wave-based information and computing technologies. For practical devices, it is essential to develop the excitation techniques for different types of surface acoustic waves, especially at higher microwave frequencies, and to tailor their frequency versus wave vector characteristics. We show that this can be done by using ultrashort laser pulses incident on the surface of a multilayer decorated with a periodic array of metallic nanodots. Specifically, we study surface acoustic waves in the dielectric substrate Si/SiO2 decorated with a square lattice of thin Ni80Fe20 (Py) dots. Using a femtosecond laser-based optical pump–probe measurement, we detect a number of high-frequency phononic modes. By performing finite element simulations, we identify them as Sezawa modes from the second and third Brillouin zone in addition to the modes confined within the Py dots. The frequency of the Sezawa modes strongly depends on the period of the Py dots and varies in the range between 5 to 15 GHz. Both types of waves cover the same frequency range for Py dots with period less than 400 nm, providing a promising system for magnetoelastic studies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Surface acoustic waves have emerged as one of the potential candidates for the development of next-generation wave-based information and computing technologies. For practical devices, it is essential to develop the excitation techniques for different types of surface acoustic waves, especially at higher microwave frequencies, and to tailor their frequency versus wave vector characteristics. We show that this can be done by using ultrashort laser pulses incident on the surface of a multilayer decorated with a periodic array of metallic nanodots. Specifically, we study surface acoustic waves in the dielectric substrate Si/SiO2 decorated with a square lattice of thin Ni80Fe20 (Py) dots. Using a femtosecond laser-based optical pump–probe measurement, we detect a number of high-frequency phononic modes. By performing finite element simulations, we identify them as Sezawa modes from the second and third Brillouin zone in addition to the modes confined within the Py dots. The frequency of the Sezawa modes strongly depends on the period of the Py dots and varies in the range between 5 to 15 GHz. Both types of waves cover the same frequency range for Py dots with period less than 400 nm, providing a promising system for magnetoelastic studies. |
| 311. | K Y Guslienko, Elena V. Tartakovskaya Hopf index of the toroidal magnetic hopfions in cylindrical and spherical dots Low Temperature Physics, 51 (6), pp. 695-699, 2025, ISSN: 1063-777X. @article{10.1063/10.0036746, title = {Hopf index of the toroidal magnetic hopfions in cylindrical and spherical dots}, author = {K Y Guslienko and Elena V. Tartakovskaya}, url = {https://doi.org/10.1063/10.0036746}, doi = {10.1063/10.0036746}, issn = {1063-777X}, year = {2025}, date = {2025-01-01}, journal = {Low Temperature Physics}, volume = {51}, number = {6}, pages = {695-699}, abstract = {Topologically non-trivial 3D magnetization textures in the restricted curvilinear geometries are considered. 3D topological charges (the Hopf indices) are calculated for a particular case of 3D topological magnetic solitons, the toroidal hopfions in cylindrical and spherical ferromagnetic dots. The calculation method is based on the theory of toroidal hopfions developed within the classical field theory for infinite media. We exploited the property of the toroidal hopfions that the Hopf index density in any curvilinear coordinate system can be expressed as a Jacobian of the transformation from the toroidal coordinates to new coordinates, which match to the magnetic particle symmetry. The calculated Hopf indices are not integer and approach integer values increasing the dot sizes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Topologically non-trivial 3D magnetization textures in the restricted curvilinear geometries are considered. 3D topological charges (the Hopf indices) are calculated for a particular case of 3D topological magnetic solitons, the toroidal hopfions in cylindrical and spherical ferromagnetic dots. The calculation method is based on the theory of toroidal hopfions developed within the classical field theory for infinite media. We exploited the property of the toroidal hopfions that the Hopf index density in any curvilinear coordinate system can be expressed as a Jacobian of the transformation from the toroidal coordinates to new coordinates, which match to the magnetic particle symmetry. The calculated Hopf indices are not integer and approach integer values increasing the dot sizes. |
| 310. | Rob den Teuling, Ritesh Das, Artem V Bondarenko, Elena V. Tartakovskaya, Gerrit E W Bauer, Yaroslav M Blanter Dipolar-exchange spin waves in thin bilayers Low Temperature Physics, 51 (8), pp. 998-1003, 2025, ISSN: 1063-777X. @article{10.1063/10.0038642, title = {Dipolar-exchange spin waves in thin bilayers}, author = {Rob den Teuling and Ritesh Das and Artem V Bondarenko and Elena V. Tartakovskaya and Gerrit E W Bauer and Yaroslav M Blanter}, url = {https://doi.org/10.1063/10.0038642}, doi = {10.1063/10.0038642}, issn = {1063-777X}, year = {2025}, date = {2025-01-01}, journal = {Low Temperature Physics}, volume = {51}, number = {8}, pages = {998-1003}, abstract = {We investigate the dipolar-exchange spin wave spectrum in thin ferromagnetic bilayers with in-plane magnetization, incorporating interlayer exchange coupling and intra- and interlayer dipolar interactions. In the continuum approximation, we analyze the nonreciprocity of propagating magnetic stray fields emitted by spin waves as a function of the relative orientation of the layer magnetizations that are observable by magnetometry of synthetic antiferromagnets or weakly coupled type-A van der Waals antiferromagnetic bilayers as a function of an applied magnetic field.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate the dipolar-exchange spin wave spectrum in thin ferromagnetic bilayers with in-plane magnetization, incorporating interlayer exchange coupling and intra- and interlayer dipolar interactions. In the continuum approximation, we analyze the nonreciprocity of propagating magnetic stray fields emitted by spin waves as a function of the relative orientation of the layer magnetizations that are observable by magnetometry of synthetic antiferromagnets or weakly coupled type-A van der Waals antiferromagnetic bilayers as a function of an applied magnetic field. |
| 309. | Yulia Kharlan, V Chernenko, O Salyuk, S Lanceros-Mendez, H Hosoda, V Golub Tensile stresses in NiMnGa laminate composite framed by soft magnetic foils Low Temperature Physics, 51 (8), pp. 1013-1016, 2025, ISSN: 1063-777X. @article{10.1063/10.0038647, title = {Tensile stresses in NiMnGa laminate composite framed by soft magnetic foils}, author = {Yulia Kharlan and V Chernenko and O Salyuk and S Lanceros-Mendez and H Hosoda and V Golub}, url = {https://doi.org/10.1063/10.0038647}, doi = {10.1063/10.0038647}, issn = {1063-777X}, year = {2025}, date = {2025-01-01}, journal = {Low Temperature Physics}, volume = {51}, number = {8}, pages = {1013-1016}, abstract = {The magnetically induced stresses in “Fe/Ni–Mn–Ga single crystalline particles/Fe” laminate composites have been studied depending on the thickness of the framing Fe foils and the distances between them. It evaluated the magnetically induced repulsive force between the two Fe foils which results in additional tensile stress of NiMnGa particles experimentally observed before. The presented calculation shows the way to improve the magnetostrain performance of laminate composite actuators.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The magnetically induced stresses in “Fe/Ni–Mn–Ga single crystalline particles/Fe” laminate composites have been studied depending on the thickness of the framing Fe foils and the distances between them. It evaluated the magnetically induced repulsive force between the two Fe foils which results in additional tensile stress of NiMnGa particles experimentally observed before. The presented calculation shows the way to improve the magnetostrain performance of laminate composite actuators. |
| 308. | Vladyslav Borynskyi, Yulia Kharlan, Roman Verba Low Temperature Physics, 51 (8), pp. 986-992, 2025, ISSN: 1063-777X. @article{10.1063/10.0038640, title = {Effect of interfacial Dzyaloshinskii–Moriya interaction on three-magnon processes in thin magnetic nanodots}, author = {Vladyslav Borynskyi and Yulia Kharlan and Roman Verba}, url = {https://doi.org/10.1063/10.0038640}, doi = {10.1063/10.0038640}, issn = {1063-777X}, year = {2025}, date = {2025-01-01}, journal = {Low Temperature Physics}, volume = {51}, number = {8}, pages = {986-992}, abstract = {Magnetic materials are familiar with their nonlinear dynamics, which becomes especially rich and efficient at the nanoscale. Precise control of nonlinear interaction is of high interest for various applications. Recently, it was shown that controllable symmetry breaking of magnetic state, induced, e.g., by a magnetic field perturbation, provides an efficient tool for manipulation of multi-magnon processes, which is especially efficient for three-magnon splitting and confluence. In this work, we investigate the effect of interfacial Dzyaloshinskii–Moriya interaction (IDMI)—an antisymmetric exchange interaction—on three-magnon processes. It is shown that IDMI affects the selection rules for three-magnon processes and their efficiency in all the considered geometries of thin magnetic nanodots: saturated magnetic dot with in-plane or perpendicular magnetization and vortex-state magnetic disk. Our results show the need for accurate consideration of possible effects of IDMI or other non-symmetric interactions when designing magnetic or spintronic devices with a controllable nonlinear response.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Magnetic materials are familiar with their nonlinear dynamics, which becomes especially rich and efficient at the nanoscale. Precise control of nonlinear interaction is of high interest for various applications. Recently, it was shown that controllable symmetry breaking of magnetic state, induced, e.g., by a magnetic field perturbation, provides an efficient tool for manipulation of multi-magnon processes, which is especially efficient for three-magnon splitting and confluence. In this work, we investigate the effect of interfacial Dzyaloshinskii–Moriya interaction (IDMI)—an antisymmetric exchange interaction—on three-magnon processes. It is shown that IDMI affects the selection rules for three-magnon processes and their efficiency in all the considered geometries of thin magnetic nanodots: saturated magnetic dot with in-plane or perpendicular magnetization and vortex-state magnetic disk. Our results show the need for accurate consideration of possible effects of IDMI or other non-symmetric interactions when designing magnetic or spintronic devices with a controllable nonlinear response. |
| 307. | Grzegorz Centała, Jarosław W. Kłos Magneto-rotation coupling for ferromagnetic nanoelement embedded in elastic substrate Journal of Applied Physics, 137 (23), pp. 233904, 2025, ISSN: 0021-8979. @article{10.1063/5.0271755b, title = {Magneto-rotation coupling for ferromagnetic nanoelement embedded in elastic substrate}, author = {Grzegorz Centała and Jarosław W. Kłos}, url = {https://doi.org/10.1063/5.0271755}, doi = {10.1063/5.0271755}, issn = {0021-8979}, year = {2025}, date = {2025-01-01}, journal = {Journal of Applied Physics}, volume = {137}, number = {23}, pages = {233904}, abstract = {This study investigates magneto-rotational coupling as a distinct contribution to magnetoelastic interactions, which can be influenced by magnetic anisotropy. We determine magneto-rotational coupling coefficients that incorporate the shape anisotropy of a magnetic nanoelement (strip) and demonstrate that this type of coupling can be modified through geometric adjustments. Furthermore, we analyze the magneto-rotational contribution to the magnetoelastic field in a ferromagnetic strip embedded in a nonmagnetic substrate. Both Rayleigh and Love waves are considered sources of the magnetoelastic field, and we examine how the strength of the magneto-rotational coupling varies with the direction of the magnetization, and the aspect ratio of the strip cross section. We analyze the changes in the magneto-rotational contribution to the magnetoelastic field with an increasing thickness-to-width ratio, assuming a fixed magnetization direction corresponding to the strongest magnetoelastic coupling. For Love waves, the contribution of the out-of-plane component increases monotonically, while that of the in-plane component decreases monotonically. In the case of the Rayleigh wave, only the out-of-plane component contributes, and it approaches zero as the cross section becomes square. These findings enhance the understanding of magneto-rotational coupling in magnonic nanostructures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This study investigates magneto-rotational coupling as a distinct contribution to magnetoelastic interactions, which can be influenced by magnetic anisotropy. We determine magneto-rotational coupling coefficients that incorporate the shape anisotropy of a magnetic nanoelement (strip) and demonstrate that this type of coupling can be modified through geometric adjustments. Furthermore, we analyze the magneto-rotational contribution to the magnetoelastic field in a ferromagnetic strip embedded in a nonmagnetic substrate. Both Rayleigh and Love waves are considered sources of the magnetoelastic field, and we examine how the strength of the magneto-rotational coupling varies with the direction of the magnetization, and the aspect ratio of the strip cross section. We analyze the changes in the magneto-rotational contribution to the magnetoelastic field with an increasing thickness-to-width ratio, assuming a fixed magnetization direction corresponding to the strongest magnetoelastic coupling. For Love waves, the contribution of the out-of-plane component increases monotonically, while that of the in-plane component decreases monotonically. In the case of the Rayleigh wave, only the out-of-plane component contributes, and it approaches zero as the cross section becomes square. These findings enhance the understanding of magneto-rotational coupling in magnonic nanostructures. |