Gate-tunable magnetoresistance in six-septuple-layer MnBi$_2$Te$_4$

TL;DR

This study investigates how gate voltage influences magnetoresistance in six-layer MnBi$_2$Te$_4$, revealing complex magnetic and topological interactions with potential for tunable quantum phases.

Contribution

It provides the first systematic analysis of gate-dependent magnetotransport in multilayer MnBi$_2$Te$_4$, highlighting the interplay between magnetic states and topological properties.

Findings

Positive linear magnetoresistance in p-type regime under ferromagnetic polarization

Negative magnetoresistance observed in n-type regime

Magnetoresistance behavior transitions with gate voltage within the antiferromagnetic state

Abstract

The recently discovered antiferromagnetic topological insulator MnBi$_2$Te$_4$ hosts a variety of exotic topological quantum phases such as the axion insulator and Chern insulator states. Here we report systematic gate voltage dependent magneto transport studies in six septuple-layer MnBi$_2$Te$_4$. In p-type carrier regime, we observe positive linear magnetoresistance when MnBi$_2$Te$_4$ is polarized in the ferromagnetic state by an out-of-plane magnetic field. Whereas in n-type regime, distinct negative magnetoresistance behaviors are observed. The magnetoresistance in both regimes is highly robust against temperature even up to the N\'eel temperature. Within the antiferromagnetic state, the behavior of magnetoresistance exhibits a transition from negative to positive as applying a gate voltage. The boundaries between different magnetoresistance behaviors in the experimental phase diagram can be explicitly characterized by the gate-voltage-independent magnetic fields that denotes the processes of the spin-flop transition. The rich transport phenomena demonstrate the intricate interplay between topology, magnetism and dimensionality in MnBi$_2$Te$_4$.