Gippius, A. A.; Zhurenko, S. V.; Tkachev, A. V.; Gunbin, A. V.; Büttgen, N.; Schaedler, M.; Silkin, I. G.; Morozov, I. V.; Bogach, A. V.; Sobolev, A. V.; Presniakov, I. A.; Moskvin, A. S. Short-range helical magnetic order in FeP1-xAsx (x = 0.33 and 0.5) Journal Article J. Magn. Magn. Mater. 651, 174177 (2026). @article{GIPPIUS2026174177,
title = {Short-range helical magnetic order in FeP_{1-x}As_{x} (x = 0.33 and 0.5)},
author = {A. A. Gippius and S. V. Zhurenko and A. V. Tkachev and A. V. Gunbin and N. Büttgen and M. Schaedler and I. G. Silkin and I. V. Morozov and A. V. Bogach and A. V. Sobolev and I. A. Presniakov and A. S. Moskvin},
url = {https://www.sciencedirect.com/science/article/pii/S0304885326003689},
doi = {10.1016/j.jmmm.2026.174177},
year = {2026},
date = {2026-08-01},
urldate = {2026-08-01},
journal = {J. Magn. Magn. Mater.},
volume = {651},
pages = {174177},
abstract = {Although the FeP1-xAsx solid solution compounds are isostructural with the binary helimagnets FeP and FeAs with MnP-type structure (sp. gr. Pnma) of the B31 family, their magnetic structure remained unclear. We studied two members of this family (x = 0.33 and 0.5) via microscopic site-selective techniques such as Mössbauer and NMR spectroscopy. Our results indicate that the helimagnetic nature of the ground state is preserved, but undergoes significant modifications. In particular, its ordering range seems to become drastically shorter, so that the local fields on the non-magnetic phosphorus atoms decrease several times compared to those in FeP, and even local fields on iron slightly decrease compared to FeP and FeAs. The ordering temperature for these fragmented structures is suppressed down to 20–30 K, which is significantly lower than the TN values for FeP and FeAs. Additionally, both compounds demonstrate higher sustainability to the external field than the parent compound FeP.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Although the FeP1-xAsx solid solution compounds are isostructural with the binary helimagnets FeP and FeAs with MnP-type structure (sp. gr. Pnma) of the B31 family, their magnetic structure remained unclear. We studied two members of this family (x = 0.33 and 0.5) via microscopic site-selective techniques such as Mössbauer and NMR spectroscopy. Our results indicate that the helimagnetic nature of the ground state is preserved, but undergoes significant modifications. In particular, its ordering range seems to become drastically shorter, so that the local fields on the non-magnetic phosphorus atoms decrease several times compared to those in FeP, and even local fields on iron slightly decrease compared to FeP and FeAs. The ordering temperature for these fragmented structures is suppressed down to 20–30 K, which is significantly lower than the TN values for FeP and FeAs. Additionally, both compounds demonstrate higher sustainability to the external field than the parent compound FeP. |
Lamp, M.; Ebad-Allah, J.; Chmeruk, A.; Bura, N.; Schönemann, R.; Balicas, L.; Lee, S. H.; Mao, Z. Q.; Chioncel, L.; Kuntscher, C. A. Charge dynamics in the Weyl semimetals NbIrTe4 and TaIrTe4 under pressure: Signatures of an electronic phase transition Unpublished (2026), arXiv:2606.02085. @unpublished{lamp:ChargeDynamics2026,
title = {Charge dynamics in the Weyl semimetals NbIrTe_{4} and TaIrTe_{4} under pressure: Signatures of an electronic phase transition},
author = {M. Lamp and J. Ebad-Allah and A. Chmeruk and N. Bura and R. Schönemann and L. Balicas and S. H. Lee and Z. Q. Mao and L. Chioncel and C. A. Kuntscher},
url = {https://arxiv.org/abs/2606.02085},
doi = {10.48550/arXiv.2606.02085},
year = {2026},
date = {2026-06-01},
urldate = {2026-06-01},
abstract = {A high-pressure investigation of the Weyl semimetals NbIrTe4 and TaIrTe4 is presented, using infrared spectroscopy supplemented by density functional theory calculations. The experimental optical conductivity spectra as a function of pressure suggest the occurrence of a pressure-induced phase transition at a critical pressure P_c = 7-8 GPa. This transition is most likely electronic in nature, as Raman scattering measurements provide no evidence of a significant structural phase transition. Above P_c a significant redistribution of spectral weight occurs in the optical conductivity spectrum for both materials. A Drude-Lorentz analysis of the optical data indicates a sharp reduction in the free carrier concentration at P_c, concomitant with the appearance of a low-energy phonon, which was initially screened by free charge carriers. A predominantly electronic origin of the phase transition is supported by the calculated electronic band structure, Fermi surface, and interband optical conductivity as a function of pressure. Our findings provide collective evidence for a pressure-induced, most likely electronic phase transition in both van der Waals materials at P_c=7-8 GPa, highlighting the tunability of their electronic band structure by hydrostatic pressure.},
note = { arXiv:2606.02085},
keywords = {},
pubstate = {published},
tppubtype = {unpublished}
}
A high-pressure investigation of the Weyl semimetals NbIrTe4 and TaIrTe4 is presented, using infrared spectroscopy supplemented by density functional theory calculations. The experimental optical conductivity spectra as a function of pressure suggest the occurrence of a pressure-induced phase transition at a critical pressure P_c = 7-8 GPa. This transition is most likely electronic in nature, as Raman scattering measurements provide no evidence of a significant structural phase transition. Above P_c a significant redistribution of spectral weight occurs in the optical conductivity spectrum for both materials. A Drude-Lorentz analysis of the optical data indicates a sharp reduction in the free carrier concentration at P_c, concomitant with the appearance of a low-energy phonon, which was initially screened by free charge carriers. A predominantly electronic origin of the phase transition is supported by the calculated electronic band structure, Fermi surface, and interband optical conductivity as a function of pressure. Our findings provide collective evidence for a pressure-induced, most likely electronic phase transition in both van der Waals materials at P_c=7-8 GPa, highlighting the tunability of their electronic band structure by hydrostatic pressure. |
Zhao, K.; Deng, H.; Chen, H.; Ma, N.; Oefele, N.; Guo, J.; Cui, X.; Tang, C.; Gutmann, M. J.; Mueller, T.; Su, Y.; Hutanu, V.; Jin, C.; Gegenwart, P. Three-dimensional XY universality and nonlinear magnetic susceptibility in a kagome ice compound Journal Article Phys. Rev. X 16, 021043 (2026). @article{xl5f-zj9p,
title = {Three-dimensional XY universality and nonlinear magnetic susceptibility in a kagome ice compound},
author = {K. Zhao and H. Deng and H. Chen and N. Ma and N. Oefele and J. Guo and X. Cui and C. Tang and M. J. Gutmann and T. Mueller and Y. Su and V. Hutanu and C. Jin and P. Gegenwart},
url = {https://link.aps.org/doi/10.1103/xl5f-zj9p},
doi = {10.1103/xl5f-zj9p},
year = {2026},
date = {2026-05-26},
urldate = {2026-05-01},
journal = {Phys. Rev. X},
volume = {16},
number = {2},
pages = {021043},
abstract = {Kagome spin ice is an intriguing class of spin systems constituted by in-plane Ising spins with ferromagnetic interaction residing on the kagome lattice, theoretically predicted to host a plethora of magnetic transitions and excitations. In particular, different variants of kagome spin ice models can exhibit different sequences of symmetry breaking upon cooling from the paramagnetic to the fully ordered ground state. Recently, it has been demonstrated that the frustrated intermetallic HoAgGe stands as a faithful solid-state realization of kagome spin ice. However, whether any of the established symmetry-breaking pathways apply to this material remains unaddressed. Here, we use single-crystal neutron diffuse scattering to map the spin ordering of HoAgGe at various temperatures more accurately; surprisingly, we find that the ordering sequence appears to be different from previously known scenarios: From the paramagnetic state, the system first enters a partially ordered state with fluctuating magnetic charges, in contrast to a charge-ordered paramagnetic phase, before reaching the fully ordered state. Through Monte Carlo simulations and scaling analyses using an extended three-dimensional (3D) spin model for the distorted kagome spin ice in HoAgGe, we elucidate a single 3D XY phase transition into the ground state with broken time-reversal symmetry (TRS). However, the 3D XY transition has a long crossover tail before the fluctuating magnetic charges fully order. More interestingly, we find, both experimentally and theoretically, that the TRS-breaking phase of HoAgGe features an unusual, hysteretic response: Despite their vanishing magnetization, the two time-reversal partners are distinguished and selected by a nonlinear magnetic susceptibility tied to the kagome ice rule. Our discovery not only unveils a new symmetry-breaking hierarchy of kagome spin ice but also demonstrates the potential of TRS-breaking frustrated spin systems for information technology applications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Kagome spin ice is an intriguing class of spin systems constituted by in-plane Ising spins with ferromagnetic interaction residing on the kagome lattice, theoretically predicted to host a plethora of magnetic transitions and excitations. In particular, different variants of kagome spin ice models can exhibit different sequences of symmetry breaking upon cooling from the paramagnetic to the fully ordered ground state. Recently, it has been demonstrated that the frustrated intermetallic HoAgGe stands as a faithful solid-state realization of kagome spin ice. However, whether any of the established symmetry-breaking pathways apply to this material remains unaddressed. Here, we use single-crystal neutron diffuse scattering to map the spin ordering of HoAgGe at various temperatures more accurately; surprisingly, we find that the ordering sequence appears to be different from previously known scenarios: From the paramagnetic state, the system first enters a partially ordered state with fluctuating magnetic charges, in contrast to a charge-ordered paramagnetic phase, before reaching the fully ordered state. Through Monte Carlo simulations and scaling analyses using an extended three-dimensional (3D) spin model for the distorted kagome spin ice in HoAgGe, we elucidate a single 3D XY phase transition into the ground state with broken time-reversal symmetry (TRS). However, the 3D XY transition has a long crossover tail before the fluctuating magnetic charges fully order. More interestingly, we find, both experimentally and theoretically, that the TRS-breaking phase of HoAgGe features an unusual, hysteretic response: Despite their vanishing magnetization, the two time-reversal partners are distinguished and selected by a nonlinear magnetic susceptibility tied to the kagome ice rule. Our discovery not only unveils a new symmetry-breaking hierarchy of kagome spin ice but also demonstrates the potential of TRS-breaking frustrated spin systems for information technology applications. |
Mukharjee, P. K.; Erdmann, S.; Wang, L.; Kaiser, J.; Jesche, A.; Puphal, P.; Isobe, M.; Hepting, M.; Keimer, Bernhard; Gegenwart, P.; Tsirlin, A. A. Anisotropic magnetoelastic coupling in the honeycomb magnet Na3Co2SbO6 Journal Article Phys. Rev. B 113, (2026). @article{mukharjee2026anisotropicmagnetoelasticcouplinghoneycomb,
title = {Anisotropic magnetoelastic coupling in the honeycomb magnet Na_{3}Co_{2}SbO_{6}},
author = {P. K. Mukharjee and S. Erdmann and L. Wang and J. Kaiser and A. Jesche and P. Puphal and M. Isobe and M. Hepting and Bernhard Keimer and P. Gegenwart and A. A. Tsirlin},
url = {https://doi.org/10.1103/tn1m-sjdh},
doi = {10.1103/tn1m-sjdh},
year = {2026},
date = {2026-05-26},
urldate = {2026-05-01},
journal = {Phys. Rev. B},
volume = {113},
number = {20},
abstract = {We present magnetization and dilatometry measurements on the honeycomb cobaltate Na3Co2SbO6 and map out its detailed field-temperature phase diagram down to sub-Kelvin temperatures. Our data for in-plane magnetic fields show a strongly anisotropic 𝑐*-axis lattice response, which is dominated by the variation of Co–O–Co bond angles according to ab initio calculations. At 𝑇=0.4K, the magnetization 𝑀(𝐵) exhibits steplike features that are also highly anisotropic. In the case of 𝐵∥𝑏, a small hysteresis observed around the second field-induced magnetic transition (𝐵𝑐2) indicates its first-order character, whereas the apparent divergence of the magnetic Grüneisen parameter at 𝐵𝑐2 is suppressed upon cooling and signals the absence of quantum critical behavior upon entering the field-polarized state. None of our thermodynamic measurements provide evidence for a field-induced quantum spin-liquid state near or above 𝐵𝑐2.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present magnetization and dilatometry measurements on the honeycomb cobaltate Na3Co2SbO6 and map out its detailed field-temperature phase diagram down to sub-Kelvin temperatures. Our data for in-plane magnetic fields show a strongly anisotropic 𝑐*-axis lattice response, which is dominated by the variation of Co–O–Co bond angles according to ab initio calculations. At 𝑇=0.4K, the magnetization 𝑀(𝐵) exhibits steplike features that are also highly anisotropic. In the case of 𝐵∥𝑏, a small hysteresis observed around the second field-induced magnetic transition (𝐵𝑐2) indicates its first-order character, whereas the apparent divergence of the magnetic Grüneisen parameter at 𝐵𝑐2 is suppressed upon cooling and signals the absence of quantum critical behavior upon entering the field-polarized state. None of our thermodynamic measurements provide evidence for a field-induced quantum spin-liquid state near or above 𝐵𝑐2. |
Mukharjee, P. K.; Erdmann, S.; Kalaivanan, R.; Sankar, R.; Choi, K. -Y.; Tsirlin, A. A.; Gegenwart, P. Thermodynamic signatures of a field-induced ordered intermediate phase in Na2Co2TeO6 Unpublished (2026), arXiv:2605.15829. @unpublished{mukharjee2026thermodynamicsignaturesfieldinducedordered,
title = {Thermodynamic signatures of a field-induced ordered intermediate phase in Na_{2}Co_{2}TeO_{6}},
author = {P. K. Mukharjee and S. Erdmann and R. Kalaivanan and R. Sankar and K. -Y. Choi and A. A. Tsirlin and P. Gegenwart},
url = {https://arxiv.org/abs/2605.15829},
doi = {10.48550/arXiv.2605.15829},
year = {2026},
date = {2026-05-15},
urldate = {2026-05-01},
note = {arXiv:2605.15829},
keywords = {},
pubstate = {published},
tppubtype = {unpublished}
}
|
