Hidden Weyl Points in Centrosymmetric Paramagnetic Metals

TL;DR

This paper reveals that applying a magnetic field to certain centrosymmetric paramagnetic metals induces the formation of hidden type-II Weyl points, which may explain their anomalous magnetoresistance behavior.

Contribution

It demonstrates that magnetic fields can induce Weyl points in these materials, providing new insights into their topological properties and magnetoresistance phenomena.

Findings

Type-II Weyl points form under magnetic field application

Materials are weak topological insulators without magnetic field

Weyl points are identified through symmetry and numerical models

Abstract

The transition metal dipnictides TaAs2 , TaSb2 , NbAs2 and NbSb2 have recently sparked interest for exhibiting giant magnetoresistance. While the exact nature of magnetoresistance in these materials is still under active investigation, there are experimental results indicating anisotropic negative magnetoresistance. We study the effect of magnetic field on the band structure topology of these materials by applying a Zeeman splitting. In the absence of magnetic field, we find that the materials are weak topological insulators, which is in agreement with previous studies. When the magnetic field is applied, we find that type-II Weyl points form. This result is found first from a symmetry argument, and then numerically for a k.p model of TaAs2 and a tight-binding model of NbSb2. This effect can be of help in search for an explanation of the anomalous magnetoresistance in these materials.