The discovery of Berry curvature (BC) has spurred a tremendous surge of research into various quantum phenomena such as the anomalous transport of electrons and the topological phases of matter. In two-dimensional crystalline systems, the conventional definition of the BC lacks the in-plane components and thus it cannot explain the transverse transport along the plane-normal direction. Here, we modify the BC to newly provide in-plane components in two dimensions, giving rise to the vertical Hall effects that describe out-of-plane transports in response to in-plane perturbations and their Onsager reciprocity. Our first-principles calculations show that a large in-plane BC can appear even in an atomic-thick GdAg2 monolayer, and a hexagonal BiAg2 monolayer can host a large BC dipole known to vanish in the conventional BC. The quantum transports driven by the hitherto-hidden BC will become more significant in recently emerging two-dimensional platforms, including van der Waals heterostructures.
The layer Hall effect describes electrons spontaneously deflected to opposite sides at different layers, which has been experimentally reported in the MnBi$_2$Te$_4$ thinfilms under perpendicular electric fields [Gao et al., Nature 595, 521 (2021)]. Here, we reveal a universal origin of the layer Hall effect in terms of the so-called hidden Berry curvature, as well as material design principles. Hence, it gives rise to zero Berry curvature in momentum space but nonzero layer-locked hidden Berry curvature in real space. We show that compared to that of a trivial insulator, the layer Hall effect…
Electronic Hall viscosity: hidden indicator for antiferromagnets
High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences（中国科学院合肥物质科学研究院）；University of Science and Technology of China（中国科学技术大学）；Anhui University（安徽大学）
Harnessing hidden quantum metric response in a 2D magnet via nonlocal photovoltaic effect
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）；School of Electronics and Information Engineering, Tiangong University（天津工业大学电子信息工程学院）；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）；Institute of Physical Science and Information Technology, Anhui University（安徽大学物理科学与技术学院）；Anhui Provincial Key Laboratory of Magnetic Functional Materials and Devices, Anhui University（安徽大学安徽省磁性功能材料与器件重点实验室）；Key Laboratory of Materials Physics, Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences（中国科学院合肥物质科学研究院固体物理研究所材料物理重点实验室）；National Laboratory of Solid-State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学物理学院固态微结构国家重点实验室先进微结构协同创新中心）；School of Physics, Zhejiang University（浙江大学物理学院）
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）
