image: Sketch of planar Hall effect (PHE) in topological Weyl semimetals with magnetic and electric fields aligned in the same direction. In this case, the trace of the PHE conductivity Tr[X] is in direct proportion to the Chern number of the WP, and is robust against many system details, leading to a flat plateau at low energy.
Credit: ©Science China Press
This study is led by Prof. Yugui Yao (School of Physics, Beijing Institute of Technology) and Prof. Zhi-Ming Yu (School of Physics, Beijing Institute of Technology). Both numerical calculations and rigorous theoretical derivations were performed.
The planar Hall effect (PHE), where the magnetic field, the driving electric field, and the transverse Hall current are in the same plane, has attracted increasing interest in recent years. Various PHEs have been reported, such as linear and nonlinear, intrinsic and extrinsic PHEs. It also has been demonstrated that all these PHEs are greatly enhanced in topological semimetals, as they have contribution from the local geometric quantities, such as Berry curvature and its polarization. However, the essential physics underlying the topological semimetals is global topological quantities, namely, the quantized topological charge. The relationship between the PHE effect and these global topological quantities remains elusive.
Based on semiclassical Boltzmann theory, the research team led by Prof. Yugui Yao and Prof. Zhi-Ming Yu from Beijing Institute of Technology investigated the PHE in charge-n Weyl points (C-n WPs) with energy tilt and revealed a previously undiscovered quantized PHE plateau. When aligning the magnetic and electric fields in the same direction, they demonstrated that the trace of the PHE conductivity (Tr[X]), contributed by the Berry curvature and orbital moment, is quantized for all the C-n Weyl points, a result stemming from the global topology of the Weyl points. This quantized plateau is also robust against various material details. The analytical derivation of Tr[X] shows that it is fully determined by the Chern number and the energy tilt of the WPs. This feature becomes increasingly more precise when the Fermi energy approaches the WPs. By unveiling a novel magnetotransport phenomenon directly related to the global quantities of WP in magnetic Weyl semimetals, their work deepens the understanding of the PHE, and provides a promising method to detect the topological charge and the energy tilt of the WPs.
See the article:
Planar Hall plateau in magnetic Weyl semimetals
https://doi: 10.1016/j.scib.2024.11.026
Journal
Science Bulletin