Emergent altermagnetism at surfaces of antiferromagnets: full symmetry classification and material identification
Johannes Gutenberg University Mainz（约翰内斯·古腾堡美因茨大学）；Max Planck Institute for the Physics of Complex Systems（马克斯·普朗克复杂系统物理研究所）；Max Planck Institute for Chemical Physics of Solids（马克斯·普朗克固体化学物理研究所）；Texas A&M University（德克萨斯农工大学）；University of Münster（明斯特大学）
Colin Lange, Rodrigo Jaeschke-Ubiergo, Atasi Chakraborty, Xanthe H. Verbeek, Libor Šmejkal, Jairo Sinova, Alexander Mook
备注：
updated version containing screening of latest MAGNDATA database, a discussion of surface relaxation and reconstruction, and a discussion of surfac terraces
We demonstrate the emergence of altermagnetism at the surfaces of antiferromagnets, vastly expanding the number of material candidates with altermagnetic characteristics and establishing a route towards two-dimensional altermagnetism through surface-induced symmetry breaking. We do so by developing a surface spin group formalism that fully classifies all surface magnetic states and identifies altermagnetic surface spin groups that can arise at the surfaces of antiferromagnets. We use this formalism to identify over 150 antiferromagnetic entries from the MAGNDATA database with at least one altermagnetic surface, often times with multiple such surfaces in the same material, and clarify the role of surface roughness and terraces. We illustrate this emergent phenomenon in a realistic Lieb lattice-based minimal model and present ab initio calculations on two representative material candidates, $\text{NaMnP}$ and $\text{FeGe}_2$, exhibiting $d$-wave and $g$-wave surface altermagnetism, respectively. Our theory naturally resolves the contradiction of recent experimental reports of $d$-wave spin splitting from ARPES measurements on metallic Lieb lattice compounds such as KV$_2$Se$_2$O that have been shown to be antiferromagnetic in the bulk. Hence, we establish a new paradigm for generating effectively two-dimensional altermagnetism by functionalizing the abundant material class of collinear antiferromagnets as viable platforms for controlled surface altermagnetism.
Emergence and Detection of Surface altermagnetism in KV$_2$Se$_2$O
Institute of Physics, Johannes Gutenberg University Mainz（约翰内斯·古腾堡大学美因茨物理研究所）；University of Münster, Institute of Solid State Theory（明斯特大学固理论研所）；Department of Physics, Texas A&M University（德克萨斯农工大学物理系）
Unlocking Doping Effects on Altermagnetism in MnTe: Emergence of Quasi-altermagnetism
Indian Institute of Technology Madras（印度马德拉斯理工学院）；Indian Institute of Science, Bangalore（印度科学研究所班加罗尔分校）；Scuola Internazionale Superiore di Studi Avanzati (SISSA)（国际高等研究院）
Atomic-scale visualization of d-wave altermagnetism
Tsinghua University（清华大学）；Frontier Science Center for Quantum Information（量子信息前沿科学中心）；Beijing Institute of Technology（北京理工大学）；Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）；Southern University of Science and Technology（南方科技大学）；Hefei National Laboratory（合肥国家实验室）
Robust and tunable Floquet altermagnets in sliding A-type antiferromagnetic bilayers
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，凝聚态物理北京国家实验室）；Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (Ministry of Education), School of Physics, Beijing Institute of Technology（北京理工大学物理学院，先进光电子量子架构与测量教育部重点实验室，量子物理中心）；University of Chinese Academy of Sciences（中国科学院大学）；Songshan Lake Materials Laboratory（松山湖材料实验室）
Altermagnetism, ARPES, symmetry, non-relativistic band splitting
Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences（中国科学院上海微系统与信息技术研究所）；University of Chinese Academy of Sciences（中国科学院大学）；National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China（中国科学技术大学核科学与技术学院及国家同步辐射实验室）；Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute（上海先进应用研究院上海同步辐射光源）
Electric-Field-Switchable Altermagnetism via Ligand Rotation in a d0 Metal-Organic Framework
School of Physics and Technology, Nanjing Normal University（南京师范大学物理科学与技术学院）；State Key Laboratory of Precision and Intelligent Chemistry, School of Chemistry and Materials Science, and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China（中国科学技术大学化学与材料科学学院精密与智能化学国家重点实验室及化学为能源材料协同创新中心）
Engineering Altermagnetism via Layer Shifts and Spin Order in Bilayer MnPS$_3$
Universidad de Antofagasta（安托法加斯塔大学）；Technische Universität Dresden（德累斯顿工业大学）；Universidad Técnica Federico Santa María（费德里科·圣塔玛丽亚技术大学）；Universidad de Chile（智利大学）；Dresden University of Technology, Institute for Solid State and Materials Physics（德累斯顿工业大学固体与材料物理研究所）
Observation of hidden altermagnetism in Cs$_{1-δ}$V$_2$Te$_2$O
Zhejiang University（浙江大学）；Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences（中国科学院上海微系统与信息技术研究所）；Southern University of Science and Technology（南方科技大学）
Projectively implemented altermagnetism in an exactly solvable quantum spin liquid
Technical University of Munich（慕尼黑工业大学）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）；University of Cologne（科隆大学）；Imperial College London（帝国理工学院）
