Misawa, R.; Kitou, S.; Yamada, R.; Gaggl, T.; Nakano, R.; Shibata, Y.; Okamura, Y.; Kriener, M.; Baral, P. R.; Nakamura, Y.; Ōnuki, Y.; Takahashi, Y.; Arima, T.; Jovanovic, M.; Schoop, L. M.; Hirschberger, M. Successive orthorhombic distortions in kagome metals by molecular orbital formation Journal Article Adv. Mater. e13015 (2025). @article{misawa_successive_2025,
title = {Successive orthorhombic distortions in kagome metals by molecular orbital formation},
author = {R. Misawa and S. Kitou and R. Yamada and T. Gaggl and R. Nakano and Y. Shibata and Y. Okamura and M. Kriener and P. R. Baral and Y. Nakamura and Y. Ōnuki and Y. Takahashi and T. Arima and M. Jovanovic and L. M. Schoop and M. Hirschberger},
url = {https://advanced.onlinelibrary.wiley.com/doi/abs/10.1002/adma.202513015},
doi = {10.1002/adma.202513015},
year = {2025},
date = {2025-12-05},
urldate = {2025-12-01},
journal = {Adv. Mater.},
pages = {e13015},
abstract = {The kagome lattice, with its inherent frustration, hosts a plethora of exotic phenomena, including the emergence of 3q charge-density-wave order. The high rotational symmetry required to realize such an unconventional charge order is broken in many kagome materials by orthorhombic distortions at high temperature, the origin of which remains much less examined despite their ubiquity. In this study, synchrotron X-ray diffraction reveals a structural phase transition from a parent hexagonal structure to an orthorhombic groundstate, mediated by a critical regime with diffuse scattering in the prototypical kagome metals RRu3Si2 (R = Nd, Pr). Structural analysis uncovers partially ordered bonds between kagome layers in the orthorhombic phases. Accordingly, a short-range correlated dimer model on the kagome layers reproduces the diffuse scattering, with the short-range order arising from competing structures induced by the geometrical frustration of the kagome lattice. The observations point to molecular orbital formation between Ru $4d_zˆ2$ orbitals as the driving force behind the transition, consistent with ab initio calculations. A framework based on electronegativity and a tolerance factor is proposed to evaluate the stability of the hexagonal phase in various kagome metals, guiding the design of highly symmetric materials.},
keywords = {B5},
pubstate = {published},
tppubtype = {article}
}
The kagome lattice, with its inherent frustration, hosts a plethora of exotic phenomena, including the emergence of 3q charge-density-wave order. The high rotational symmetry required to realize such an unconventional charge order is broken in many kagome materials by orthorhombic distortions at high temperature, the origin of which remains much less examined despite their ubiquity. In this study, synchrotron X-ray diffraction reveals a structural phase transition from a parent hexagonal structure to an orthorhombic groundstate, mediated by a critical regime with diffuse scattering in the prototypical kagome metals RRu3Si2 (R = Nd, Pr). Structural analysis uncovers partially ordered bonds between kagome layers in the orthorhombic phases. Accordingly, a short-range correlated dimer model on the kagome layers reproduces the diffuse scattering, with the short-range order arising from competing structures induced by the geometrical frustration of the kagome lattice. The observations point to molecular orbital formation between Ru $4d_zˆ2$ orbitals as the driving force behind the transition, consistent with ab initio calculations. A framework based on electronegativity and a tolerance factor is proposed to evaluate the stability of the hexagonal phase in various kagome metals, guiding the design of highly symmetric materials. |
Chmeruk, A.; Jones, D.; Balducci, R.; Ebad-Allah, J.; Beiuşeanu, F.; Schilberth, F.; Kassem, M. A.; Schade, U.; Veber, A.; Puskar, L.; Tabata, Y.; Waki, T.; Nakamura, H.; Kuntscher, C. A.; Östlin, A.; Chioncel, L. Suppression of magnetism in Co3Sn2S2 under external pressure Unpublished (2025), arXiv:2511.08141. @unpublished{chmeruk_suppression_2025,
title = {Suppression of magnetism in Co_{3}Sn_{2}S_{2} under external pressure},
author = {A. Chmeruk and D. Jones and R. Balducci and J. Ebad-Allah and F. Beiuşeanu and F. Schilberth and M. A. Kassem and U. Schade and A. Veber and L. Puskar and Y. Tabata and T. Waki and H. Nakamura and C. A. Kuntscher and A. Östlin and L. Chioncel},
url = {https://arxiv.org/abs/2511.08141},
doi = {10.48550/arXiv.2511.08141},
year = {2025},
date = {2025-11-11},
urldate = {2025-11-11},
abstract = {The ability to control the magnetic state provides a powerful means to tune the underlying band topology, enabling transitions between distinct electronic phases and the emergence of novel quantum phenomena. In this work, we address the evolution of ferromagnetic state upon applying external pressures up to 10.8~GPa using a combined experimental and theoretical study. The standard emph{ab initio} Density Functional Theory computation including ionic relaxations grossly overestimates the unit cell magnetization as a function of pressure. In our theoretical analysis we identify two possible mechanisms to remedy this shortcoming. Matching the experimental observations is achieved by a symmetry-preserving adjustment of the sulfur atoms position within the unit cell. Alternatively, we explore various combinations of the exchange and correlation parts of the effective potential which reproduce the experimental magnetization, the structural parameters and the measured optical conductivity spectra. Thus, the pressure-dependent behavior of magnetization demands a careful theoretical treatment and analysis of theoretical and experimental data. },
note = {arXiv:2511.08141},
keywords = {A1, A5},
pubstate = {published},
tppubtype = {unpublished}
}
The ability to control the magnetic state provides a powerful means to tune the underlying band topology, enabling transitions between distinct electronic phases and the emergence of novel quantum phenomena. In this work, we address the evolution of ferromagnetic state upon applying external pressures up to 10.8~GPa using a combined experimental and theoretical study. The standard emph{ab initio} Density Functional Theory computation including ionic relaxations grossly overestimates the unit cell magnetization as a function of pressure. In our theoretical analysis we identify two possible mechanisms to remedy this shortcoming. Matching the experimental observations is achieved by a symmetry-preserving adjustment of the sulfur atoms position within the unit cell. Alternatively, we explore various combinations of the exchange and correlation parts of the effective potential which reproduce the experimental magnetization, the structural parameters and the measured optical conductivity spectra. Thus, the pressure-dependent behavior of magnetization demands a careful theoretical treatment and analysis of theoretical and experimental data. |
Wu, Y.; Dai, Z.; Anand, S.; Lin, S. -H.; Yang, Q.; Wang, L.; Pollmann, F.; Zaletel, M. P. Alternating and Gaussian Fermionic Isometric Tensor Network States Journal Article PRX Quantum 6, 040324 (2025). @article{wu_alternating_2025,
title = {Alternating and Gaussian Fermionic Isometric Tensor Network States},
author = {Y. Wu and Z. Dai and S. Anand and S. -H. Lin and Q. Yang and L. Wang and F. Pollmann and M. P. Zaletel},
url = {https://link.aps.org/doi/10.1103/8ypw-c8t4},
doi = {10.1103/8ypw-c8t4},
year = {2025},
date = {2025-11-05},
urldate = {2025-11-01},
journal = {PRX Quantum},
volume = {6},
number = {4},
pages = {040324},
abstract = {Isometric tensor networks in two dimensions enable efficient and accurate study of quantum many-body states, yet the effect of the isometric restriction on the represented quantum states is not fully understood. We address this question in two main contributions. First, we introduce an improved variant of isometric tensor network states (isoTNS) in two dimensions, where the isometric arrows on the columns of the network alternate between pointing upward and downward; hence the name alternating isometric tensor network states. Second, we introduce a numerical tool—the isometric Gaussian fermionic TNS (isoGfTNS)—that incorporates isometric constraints into the framework of Gaussian fermionic tensor network states. We demonstrate in numerous ways that alternating isoTNSs represent many-body ground states of two-dimensional quantum systems significantly better than the original isoTNSs. First, we show that the entanglement in an isoTNS is mediated along the isometric arrows and that alternating isoTNSs mediate entanglement more efficiently than conventional isoTNSs. Second, alternating isoTNSs correspond to a deeper, and thus more representative, sequential-circuit construction of depth 𝒪(𝐿𝑥 ⋅𝐿𝑦) compared to the original isoTNSs of depth 𝒪(𝐿𝑥 +𝐿𝑦). Third, using the Gaussian framework and gradient-based energy minimization, we provide numerical evidence of better bond-dimension scaling and variational energy of alternating isoGfTNSs for ground states of various free-fermionic models, including the Fermi surface, the band insulator, and the 𝑝𝑥 +𝑖𝑝𝑦 mean-field superconductor. Finally, benchmarking on the transverse-field Ising model, we demonstrate that an alternating isoTNS provides substantially improved performance and stability relative to the original isoTNS for the ground-state search algorithm in interacting systems.},
keywords = {B6},
pubstate = {published},
tppubtype = {article}
}
Isometric tensor networks in two dimensions enable efficient and accurate study of quantum many-body states, yet the effect of the isometric restriction on the represented quantum states is not fully understood. We address this question in two main contributions. First, we introduce an improved variant of isometric tensor network states (isoTNS) in two dimensions, where the isometric arrows on the columns of the network alternate between pointing upward and downward; hence the name alternating isometric tensor network states. Second, we introduce a numerical tool—the isometric Gaussian fermionic TNS (isoGfTNS)—that incorporates isometric constraints into the framework of Gaussian fermionic tensor network states. We demonstrate in numerous ways that alternating isoTNSs represent many-body ground states of two-dimensional quantum systems significantly better than the original isoTNSs. First, we show that the entanglement in an isoTNS is mediated along the isometric arrows and that alternating isoTNSs mediate entanglement more efficiently than conventional isoTNSs. Second, alternating isoTNSs correspond to a deeper, and thus more representative, sequential-circuit construction of depth 𝒪(𝐿𝑥 ⋅𝐿𝑦) compared to the original isoTNSs of depth 𝒪(𝐿𝑥 +𝐿𝑦). Third, using the Gaussian framework and gradient-based energy minimization, we provide numerical evidence of better bond-dimension scaling and variational energy of alternating isoGfTNSs for ground states of various free-fermionic models, including the Fermi surface, the band insulator, and the 𝑝𝑥 +𝑖𝑝𝑦 mean-field superconductor. Finally, benchmarking on the transverse-field Ising model, we demonstrate that an alternating isoTNS provides substantially improved performance and stability relative to the original isoTNS for the ground-state search algorithm in interacting systems. |
