Gate-tunable magnetoresistance in six-septuple-layer MnBi2Te4

Abstract

The recently discovered antiferromagnetic topological insulator MnBi2Te4 hosts many exotic topological quantum phases such as the axion insulator and the Chern insulator. Here we report on systematic gate-voltage-dependent magneto-transport studies in six-septuple-layer MnBi2Te4. In the p-type carrier regime, we observe positive linear magnetoresistance (MR) when MnBi2Te4 is polarized in the ferromagnetic state by an out-of-plane magnetic field. Whereas in the n-type regime, distinct negative MR behaviors are observed. The behaviors of magnetoresistance in both regimes are highly robust against temperature up to the Néel temperature. Within the antiferromagnetic regime, the behavior of MR exhibits a transition from negative to positive under the control of gate voltage. The boundaries of the MR phase diagram can be explicitly marked by the gate-voltage-independent magnetic fields that characterize the processes of the spin-flop transition. The rich transport phenomena demonstrate the intricate interplay between topology, magnetism and dimensionality in MnBi2Te4.