In investigating the topological electronic structures of monolayer $α$-phase group V elements, we uncover a new topological phase, which is invisible in the symmetry-based topological quantum chemistry (TQC) as well as symmetry indicators (SIs). Since $α$ phase As and Sb share the same band representations at high-symmetry points, they are both trivial insulators in terms of TQC and SIs. We demonstrate, however, that there is a topological phase transition between As and Sb that involves a band-gap closing at two $k$-points on the high-symmetry $\rm{X}$-$\rmΓ$-$\rm{X}$ line. In the absence of spin-orbit coupling (SOC), As is a trivial insulator, while Sb is a Dirac semimetal with four Dirac points (DPs) located away from the high-symmetry lines. Inclusion of $S_z$-conserved SOC gaps out the Dirac points and induces a nontrivial Berry curvature and drives Sb into a high spin Chern number topological phase. The band structure of $α$-Bi differs from that of Sb by a band inversion at $Γ$, transforming Bi into a Z$_2$ topological insulator. Our study shows that quantized spin Hall conductivity can serve as a topological invariant beyond Z$_2$ for characterizing topological phases.
Dynamical axion state with hidden pseudospin Chern numbers in MnBi$_{2}$Te$_{4}$-based heterostructures
轴子是一种假想的基本粒子，最初是为了解决粒子物理学中的电荷共轭-宇称问题而提出的。有趣的是，轴子态出现在拓扑绝缘体的有效理论中，并在凝聚态物理中引起了广泛的关注。时间反演或反转对称性约束了要被量化的轴子场$θ$。当时间反演和反转对称性都被反铁磁序打破时，轴子场$θ$会随着磁场涨落而变得非量子化和动态化，这被称为动态轴子场。在这里，我们揭示了广泛的一类拓扑绝缘体为基础的动力学轴子状态可以区分从正常的绝缘体为基础的一个隐藏的量从赝自旋陈数。受最近对MnBi $_{2}$ Te $_{4}$族材料的研究的启发，我们进一步表明，这种基于拓扑绝缘体的动力学轴子态有望在基于MnBi $_{2}$ Te $_{4}$的异质结构中实现，这将极大地促进凝聚态物理中轴子电动力学的研究。
Ferroelectric Altermagnetic Chern Insulator in magnetic field: electrical control of the Chern number
International Research Centre Magtop, Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所磁顶国际研究中心）；Department of Physics, University of Guilan（吉兰大学物理系）
Hidden topology and strong quantum metric bounds in trivial systems
Hefei National Laboratory（合肥国家实验室）；University of Science and Technology of China（中国科学技术大学）；Fudan University（复旦大学）；Westlake University（西湖大学）；Great Bay University（大湾区大学）
Programmable Quantum Anomalous Hall Insulator in Twisted Crystalline Flatbands
Peking University（北京大学）；National Center for Nanoscience and Technology（国家纳米科学中心）；Shanghai Jiao Tong University（上海交通大学）；Fudan University（复旦大学）；Hefei National Laboratory（合肥国家实验室）；National Institute for Material Sciences（物质材料研究国际中心）
From hidden order to skyrmions: Quantum Hall states in an extended Hofstadter-Fermi-Hubbard model
Ludwig-Maximilians-Universität München（慕尼黑大学）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）；Université Libre de Bruxelles（布鲁塞尔自由大学）；International Solvay Institutes（国际索尔维研究所）；Collège de France（法兰西学院）；CNRS（法国国家科学研究中心）；ENS-Université PSL（巴黎高等师范学院-巴黎文理研究大学）；Sorbonne Université（索邦大学）
Fractional quantum spin Hall crystals from hidden density-wave order
University of California, Los Angeles（加州大学洛杉矶分校）；Mani L. Bhaumik Institute for Theoretical Physics, University of California Los Angeles（加州大学洛杉矶分校马尼·L·鲍姆克理论物理研究所）
Fractional Chern Insulators Transition in Non-ideal Flat Bands of Twisted Mono-bilayer Graphene
State Key Laboratory of Semiconductor Physics and Chip Technologies, Institute of Semiconductors, Chinese Academy of Sciences（中国科学院半导体研究所半导体物理与芯片技术国家重点实验室）；Center for Quantum Matter, Zhejiang University（浙江大学量子物质中心）；College of Materials Science and Opto-electronic Technology, University of Chinese Academy of Sciences（中国科学院大学材料科学与光电技术学院）
