Surface-induced linear magnetoresistance in antiferromagnetic topological insulator MnBi2Te4

TL;DR

This study reveals a surface-induced linear magnetoresistance in thick MnBi2Te4 films, linked to high-mobility surface states, with temperature-dependent behavior near the Neel temperature, challenging existing models.

Contribution

It demonstrates the existence of surface-state-induced linear magnetoresistance in thick antiferromagnetic topological insulator films, revealing new physics beyond current models.

Findings

Positive linear magnetoresistance observed up to 260 K

High-mobility surface states confirmed by nonlinear Hall effect

Suppression of LMR near the Neel temperature

Abstract

Through a thorough magneto-transport study of antiferromagnetic topological insulator MnBi2Te4 (MBT) thick films, a positive linear magnetoresistance (LMR) with a two-dimensional (2D) character is found in high perpendicular magnetic fields and temperatures up to at least 260 K. The nonlinear Hall effect further reveals the existence of high-mobility surface states in addition to the bulk states in MBT. We ascribe the 2D LMR to the high-mobility surface states of MBT, thus unveiling a transport signature of surface states in thick MBT films. A suppression of LMR near the Neel temperature of MBT is also noticed, which might suggest the gap opening of surface states due to the paramagnetic-antiferromagnetic phase transition of MBT. Besides these, the failure of the disorder and quantum LMR model in explaining the observed LMR indicates new physics must be invoked to understand this phenomenon.