Pazmino, E. I.; Feng, S.; Dhakal, R.; Rousochatzakis, I.; Winter, S. M.; Knolle, J.; Tsirlin, A. A. Beyond Kitaev exchange: textbackslashGamma'-driven magnetism in Ag3LiRh2O6 Unpublished (2026), arXiv:2610.19770. @unpublished{pazminoKitaevExchangeGammadriven2026,
title = {Beyond Kitaev exchange: textbackslashGamma'-driven magnetism in Ag_{3}LiRh_{2}O_{6}},
author = {E. I. Pazmino and S. Feng and R. Dhakal and I. Rousochatzakis and S. M. Winter and J. Knolle and A. A. Tsirlin},
url = {https://arxiv.org/abs/2610.19770},
doi = {10.48550/arXiv.2610.19770},
year = {2026},
date = {2026-10-14},
urldate = {2026-10-01},
abstract = {In Kitaev magnets, frustration arises from bond-dependent spin anisotropic interactions, which can potentially realize sought-after quantum spin liquid phases. However, material realizations with dominating Kitaev exchange are scarce and the broad parameter space of extended Kitaev models remains largely unexplored experimentally. Here, we use density-functional theory, cluster many-body, spin-wave, and density-matrix renormalization calculations to show that the recently discovered honeycomb rhodate Ag3LiRh2O6 hosts an off-diagonal exchange Γ′1 that is second in magnitude only to the ferromagnetic Kitaev exchange K1. This combination of K1 and Γ′1 explains key experimental observations, an unusually high magnetic ordering temperature of 94 K at ambient pressure and its rapid decrease under hydrostatic pressure as Ag3LiRh2O6 evolves from ferromagnetic toward zigzag order within the honeycomb planes. Our spin-wave calculations further predict an unusual topology of the magnon bands arising from the Γ′1 term in the spin Hamiltonian of the honeycomb layer. We show that the large trigonal splitting of t2g states enhances Γ′1, the hitherto underappreciated term in Kitaev magnets, and opens the way to new interesting regimes of the extended Kitaev model.},
note = {arXiv:2610.19770},
keywords = {},
pubstate = {published},
tppubtype = {unpublished}
}
In Kitaev magnets, frustration arises from bond-dependent spin anisotropic interactions, which can potentially realize sought-after quantum spin liquid phases. However, material realizations with dominating Kitaev exchange are scarce and the broad parameter space of extended Kitaev models remains largely unexplored experimentally. Here, we use density-functional theory, cluster many-body, spin-wave, and density-matrix renormalization calculations to show that the recently discovered honeycomb rhodate Ag3LiRh2O6 hosts an off-diagonal exchange Γ′1 that is second in magnitude only to the ferromagnetic Kitaev exchange K1. This combination of K1 and Γ′1 explains key experimental observations, an unusually high magnetic ordering temperature of 94 K at ambient pressure and its rapid decrease under hydrostatic pressure as Ag3LiRh2O6 evolves from ferromagnetic toward zigzag order within the honeycomb planes. Our spin-wave calculations further predict an unusual topology of the magnon bands arising from the Γ′1 term in the spin Hamiltonian of the honeycomb layer. We show that the large trigonal splitting of t2g states enhances Γ′1, the hitherto underappreciated term in Kitaev magnets, and opens the way to new interesting regimes of the extended Kitaev model. |
Prodan, L.; Evans, D. M.; Puntigam, L.; Kézsmárki, I.; Tsurkan, V. Universality of magnetic susceptibility in the conical state of kagome ferromagnet Fe3Sn2 Journal Article Appl. Phys. Lett. 129, 151905 (2026), datadoi: 10.5281/zenodo.15367272. @article{prodan2026universalitymagneticsusceptibilityconical,
title = {Universality of magnetic susceptibility in the conical state of kagome ferromagnet Fe_{3}Sn_{2}},
author = {L. Prodan and D. M. Evans and L. Puntigam and I. Kézsmárki and V. Tsurkan},
url = {https://doi.org/10.1063/5.0342307},
doi = {10.1063/5.0342307},
year = {2026},
date = {2026-10-13},
urldate = {2026-10-01},
journal = {Appl. Phys. Lett.},
volume = {129},
pages = {151905},
abstract = {We report universal behavior of the differential magnetic susceptibility (DMS) in the conical phase that mediates the spin-reorientation (SR) transition of the kagome ferromagnet Fe3Sn2. Within the SR temperature range, the DMS isotherms exhibit extremely narrow crossing regions, forming isosbestic points. Using an isosbestic-invariance analysis, we show that the isotherms collapse onto a single temperature-independent curve, revealing quadratic-in-temperature corrections to the susceptibility. Complementary field-dependent magnetic-force-microscopy measurements uncover the evolution of spin textures from stripe-like domains at low fields to isolated bubble-like domains near the isosbestic field ( textasciitilde0.6T), a behavior not previously reported in bulk Fe3Sn2 within the conical state. These findings point to a universal mechanism for the emergence of complex magnetic textures near isosbestic points, driven by the competition between magnetocrystalline anisotropy, dipolar interactions, and external magnetic field.},
note = {datadoi: 10.5281/zenodo.15367272},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report universal behavior of the differential magnetic susceptibility (DMS) in the conical phase that mediates the spin-reorientation (SR) transition of the kagome ferromagnet Fe3Sn2. Within the SR temperature range, the DMS isotherms exhibit extremely narrow crossing regions, forming isosbestic points. Using an isosbestic-invariance analysis, we show that the isotherms collapse onto a single temperature-independent curve, revealing quadratic-in-temperature corrections to the susceptibility. Complementary field-dependent magnetic-force-microscopy measurements uncover the evolution of spin textures from stripe-like domains at low fields to isolated bubble-like domains near the isosbestic field ( textasciitilde0.6T), a behavior not previously reported in bulk Fe3Sn2 within the conical state. These findings point to a universal mechanism for the emergence of complex magnetic textures near isosbestic points, driven by the competition between magnetocrystalline anisotropy, dipolar interactions, and external magnetic field. |
Liu, Y. -J.; Xu, W. -T.; Pollmann, F.; Knap, M. Information-Theoretic Principle of Emergent 1-Form Symmetries Journal Article PRX Quantum 7, (2026), datadoi: 10.5281/zenodo.17652054. @article{liuInformationTheoreticPrincipleEmergent2026,
title = {Information-Theoretic Principle of Emergent 1-Form Symmetries},
author = {Y. -J. Liu and W. -T. Xu and F. Pollmann and M. Knap},
url = {https://doi.org/10.1103/d6qf-5chk},
doi = {10.1103/d6qf-5chk},
issn = {2691-3399},
year = {2026},
date = {2026-10-09},
urldate = {2026-10-01},
journal = {PRX Quantum},
volume = {7},
number = {4},
publisher = {American Physical Society (APS)},
note = {datadoi: 10.5281/zenodo.17652054},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Schneider, M.; Butcher, T. A.; Wagner, S.; Metternich, D.; Klose, C.; Malm, E.; Battistelli, R.; Deinhart, V.; Fuchs, J.; Wittrock, S.; Karaman, T.; Joy, K. Puzhekadavil; Patra, M.; Büttner, F.; Wintz, S.; Weigand, M.; Günther, C. M.; Engel, D.; Gaal, P.; Schwarzkopf, J.; Pfau, B.; Eisebitt, S. Linear dichroic soft x-ray microscopy of ferroelectric stripe domains in epitaxial K0.6Na0.4NbO3 Journal Article Phys. Rev. B 114, L231401 (2026), datadoi: 10.5281/zenodo.22250213.. @article{schneiderLinearDichroicSoft2026,
title = {Linear dichroic soft x-ray microscopy of ferroelectric stripe domains in epitaxial K_{0.6}Na_{0.4}NbO_{3}},
author = {M. Schneider and T. A. Butcher and S. Wagner and D. Metternich and C. Klose and E. Malm and R. Battistelli and V. Deinhart and J. Fuchs and S. Wittrock and T. Karaman and K. Puzhekadavil Joy and M. Patra and F. Büttner and S. Wintz and M. Weigand and C. M. Günther and D. Engel and P. Gaal and J. Schwarzkopf and B. Pfau and S. Eisebitt},
url = {https://link.aps.org/doi/10.1103/kcjc-dtj6},
doi = {10.1103/kcjc-dtj6},
year = {2026},
date = {2026-10-02},
urldate = {2026-10-01},
journal = {Phys. Rev. B},
volume = {114},
number = {23},
pages = {L231401},
publisher = {American Physical Society},
abstract = {Functional properties of ferroelectric thin films are governed by domains that can be engineered by epitaxial strain. Soft x-ray microscopy can image domain structures with elemental and electronic sensitivity, but hitherto its application to strain-stabilized domains has been hindered by the absorption of soft x-rays in epitaxial substrates. Here, it is demonstrated how this limitation can be overcome by locally back-thinning the (110) TbScO3 substrate of epitaxial K0.6Na0.4NbO3 ferroelectric thin films to achieve soft x-ray transparency at the O K-edge around 530 eV. Strain-induced ferroelectric stripe domains with periods down to 44 nm were resolved by scanning transmission x-ray microscopy and coherent diffractive imaging by exploiting the x-ray linear dichroism of hybridized O 2𝑝–Nb 4𝑑 states, providing sensitivity to in-plane polarization components under normal incidence. The results establish soft x-ray microscopy for nanoscale imaging of epitaxial ferroelectric domain structures and open perspectives for time-resolved studies thereof.},
note = {datadoi: 10.5281/zenodo.22250213.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Functional properties of ferroelectric thin films are governed by domains that can be engineered by epitaxial strain. Soft x-ray microscopy can image domain structures with elemental and electronic sensitivity, but hitherto its application to strain-stabilized domains has been hindered by the absorption of soft x-rays in epitaxial substrates. Here, it is demonstrated how this limitation can be overcome by locally back-thinning the (110) TbScO3 substrate of epitaxial K0.6Na0.4NbO3 ferroelectric thin films to achieve soft x-ray transparency at the O K-edge around 530 eV. Strain-induced ferroelectric stripe domains with periods down to 44 nm were resolved by scanning transmission x-ray microscopy and coherent diffractive imaging by exploiting the x-ray linear dichroism of hybridized O 2𝑝–Nb 4𝑑 states, providing sensitivity to in-plane polarization components under normal incidence. The results establish soft x-ray microscopy for nanoscale imaging of epitaxial ferroelectric domain structures and open perspectives for time-resolved studies thereof. |
Mangeolle, L.; Knolle, J. Probing topology in thin films with quantum Sondheimer oscillations Journal Article Phys. Rev. B 114, 225108 (2026). @article{mangeolleProbingTopologyThin2026,
title = {Probing topology in thin films with quantum Sondheimer oscillations},
author = {L. Mangeolle and J. Knolle},
url = {https://link.aps.org/doi/10.1103/l1gl-xdvv},
doi = {10.1103/l1gl-xdvv},
year = {2026},
date = {2026-10-01},
journal = {Phys. Rev. B},
volume = {114},
number = {22},
pages = {225108},
publisher = {American Physical Society},
abstract = {Sondheimer oscillations (SO) are magnetoresistance oscillations occurring in thin films due to the commensurability between cyclotron motion and sample thickness, and are traditionally regarded as a purely semiclassical size effect. Here we develop a general quantum theory of SO for thin-film conductors in the quantum limit of a large magnetic field. We show that corrections arising from band topology modify the SO frequency, in contrast to Shubnikov–de Haas oscillations where topological information appears only in the phase. As a consequence, quantum SO provide a direct and robust probe of the full Landau level spectrum. Applying our framework to a minimal model with tunable Berry phase, we demonstrate how topology manifests itself in experimentally accessible magneto-oscillation spectra and discuss damping mechanisms including surface roughness.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Sondheimer oscillations (SO) are magnetoresistance oscillations occurring in thin films due to the commensurability between cyclotron motion and sample thickness, and are traditionally regarded as a purely semiclassical size effect. Here we develop a general quantum theory of SO for thin-film conductors in the quantum limit of a large magnetic field. We show that corrections arising from band topology modify the SO frequency, in contrast to Shubnikov–de Haas oscillations where topological information appears only in the phase. As a consequence, quantum SO provide a direct and robust probe of the full Landau level spectrum. Applying our framework to a minimal model with tunable Berry phase, we demonstrate how topology manifests itself in experimentally accessible magneto-oscillation spectra and discuss damping mechanisms including surface roughness. |
