Flat band driven competing charge and spin instabilities in the altermagnet CrSb
Donostia International Physics Center (DIPC)（多诺斯蒂亚国际物理中心）；Centro de Física de Materiales (CFM-MPC), CSIC-UPV/EHU（材料物理中心，西班牙国家研究委员会/巴斯克国立大学）；Fisika Aplikatua Saila, Gipuzkoako Ingeniaritza Eskola, University of the Basque Country (UPV/EHU)（应用物理系，吉普斯夸工程学院，巴斯克国立大学）；Department of Applied Physics, KTH Royal Institute of Technology（皇家理工学院应用物理系）；Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（凝聚态物理北京实验室，中国科学院物理研究所）；Swiss-Norwegian BeamLines at European Synchrotron Radiation Facility（欧洲同步辐射装置瑞士-挪威光束线）；European Synchrotron Radiation Facility (ESRF)（欧洲同步辐射装置）；Département de Physique et Institut Quantique, Université de Sherbrooke（物理系与量子研究所，舍布鲁克大学）
A. Korshunov, M. Alkorta, C. -Y. Lim, F. Ballester, Cong Li, Zhilin Li, D. Chernyshov, A. Bosak, M. G. Vergniory, Ion Errea, S. Blanco-Canosa
The confinement of electronic wavefunctions in momentum space can give rise to flat electronic bands, where the quenching of kinetic energy enhances the density of states and amplifies interaction effects. Such conditions are fertile ground for emergent quantum phases, as spin, charge and lattice degrees of freedom become strongly entangled. In these regimes, subtle competitions between intertwined order parameters often dictate the macroscopic ground state, producing complex and sometimes unexpected collective behavior. Here we show that the altermagnet CrSb provides a realization of this scenario, and uncover short-range charge-order fluctuations at the M point of the Brillouin zone, q*=(1/2 0), persisting above the Neel temperature (TN). Remarkably, these fluctuations collapse upon entering the magnetically ordered phase, revealing a direct and robust competition between charge and spin order. At TN, the phonon dispersion at q* develops a pronounced Kohn-like anomaly, signaling strong electron-phonon coupling in the vicinity of the magnetic transition. Below TN, exchange striction dramatically renormalizes the associated soft phonon mode by approximately ~6 meV, the largest spin-phonon coupling ever reported. First-principles calculations attribute this behavior to a strong coupling between nearly dispersionless electronic states and a phonon branch that appears unstable at the harmonic level only when no magnetic order is considered, revealing the large sensitivity of the lattice to magnetic symmetry breaking. The competition between charge and spin order parameters, amplified by flat-band physics, drives the observed phonon anomaly and its abrupt reconstruction at TN. With its chemically simple structure and symmetry-protected altermagnetic state, CrSb emerges as a model platform to explore how flat electronic bands mediate giant spin-phonon coupling and competing broken symmetries.
Topological nontrivial berry phase in altermagnet CrSb
China Jiliang University（中国计量大学）；Beijing National Laboratory for Condensed Matter Physics and Institute of physics, Chinese Academy of Sciences（中国科学院物理研究所北京凝聚态物理国家研究中心）；University of Chinese Academy of Sciences（中国科学院大学）；Beijing Polytechnic College（北京工业职业技术学院）；School of Physics, Zhejiang University（浙江大学物理学院）；School of Physics, Hangzhou Normal University（杭州师范大学物理学院）；Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences（中国科学院合肥物质科学研究院强磁场科学中心）
Loss of altermagnetic order and smooth restoration of Kramers' spin degeneracy with increasing temperature in CrSb and MnTe
H.H. Wills Physics Laboratory, University of Bristol（布里斯托大学 H.H. 威尔斯物理实验室）；Department of Physics, University of Warwick（华威大学物理系）；Institute for Theoretical Physics, Johannes Keppler University Linz（林茨约翰内斯·开普勒大学理论物理研究所）；Donostia International Physics Center（圣塞巴斯蒂安国际物理中心）；Max-Planck-Institut für Mikrostrukturphysik（马克斯·普朗克微结构物理研究所）
Andreev Reflection to Probe Momentum-Dependent Spin Polarization in Altermagnet CrSb
Center for Correlated Matter and School of Physics, Zhejiang University（浙江大学关联物质研究中心和物理学院）；State Key Laboratory of Quantum Functional Materials, School of Physical Science and Technology, ShanghaiTech University（上海科技大学物理科学与技术学院量子功能材料国家重点实验室）；ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University（上海科技大学拓扑物理实验室）；Institute of Fundamental and Transdisciplinary Research, Zhejiang University（浙江大学基础与交叉研究院）
3D bulk-resolved $g$-wave altermagnetic order parameter in CrSb
Cavendish Laboratory, University of Cambridge（剑桥大学卡文迪什实验室）；Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf（德累斯顿强磁场实验室（HLD-EMFL），德累斯顿-罗斯多夫亥姆霍兹中心）；National High Magnetic Field Laboratory（国家高磁场实验室）
研究 CrSb 中非常规磁体的序参量对称性，通过磁量子振荡测量，在 CrSb 布里渊区不同方向旋转磁场，利用其反铁磁带结构特性，精确映射序参量对称性，确立 CrSb 为典型 g 波金属反铁磁体。
Observation of anomalous thermal Hall effect in altermagnets
Fudan University（复旦大学）；Shanghai Research Center for Quantum Sciences（上海量子科学研究与创新中心）；ShanghaiTech University（上海科技大学）；Hefei National Laboratory（合肥国家实验室）；Collaborative Innovation Center of Advanced Microstructures（先进微结构协同创新中心）
Many-Body Amplification of Ligand Instabilities Driving Verwey-Type Transitions in Altermagnet CsCr$_2$S$_2$O
University of Science and Technology of China（中国科学技术大学）；Hefei National Laboratory（合肥国家实验室）；New Cornerstone Science Laboratory, University of Science and Technology of China（中国科学技术大学新Cornerstone科学实验室）
Splitting of electronic spectrum in paramagnetic phase of itinerant ferromagnets and altermagnets
Moscow Institute of Physics and Technology（莫斯科物理技术学院）；M. N. Mikheev Institute of Metal Physics of the Ural Branch of the Russian Academy of Sciences（俄罗斯科学院乌拉尔分校 M.N. 米凯耶夫金属物理研究所）
Discovery of a symmetry-driven electronic cascade in a $d$-wave altermagnet
Southern University of Science and Technology（南方科技大学）；The Hong Kong University of Science and Technology（香港科技大学）；Zhejiang University（浙江大学）；Songshan Lake Materials Laboratory（松山湖材料实验室）；Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area（粤港澳大湾区量子科学中心）
