Electronic states and magnetic response of MnBi2Te4 by scanning tunneling microscopy and spectroscopy

TL;DR

This study uses low-temperature scanning tunneling microscopy to explore the surface electronic states and magnetic responses of MnBi2Te4, revealing complex surface structures, dopant effects, and implications for magnetic topological insulator design.

Contribution

It provides new insights into the surface electronic structures and magnetic behaviors of MnBi2Te4, highlighting modifications due to sample cleaving and Mn doping effects.

Findings

Surface electronic structures differ from expected antiferromagnetic phase.

Topological surface states may be embedded in deeper layers.

Atomic-scale electronic fluctuations influence magnetic properties.

Abstract

Exotic quantum phenomena have been demonstrated in recently discovered intrinsic magnetic topological insulator MnBi2Te4. At its two-dimensional limit, quantum anomalous Hall (QAH) effect and axion insulator state are observed in odd and even layers of MnBi2Te4, respectively. The measured band structures exhibit intriguing and complex properties. Here we employ low-temperature scanning tunneling microscopy to study its surface states and magnetic response. The quasiparticle interference patterns indicate that the electronic structures on the topmost layer of MnBi2Te4 is different from that of the expected out-of-plane A-type antiferromagnetic phase. The topological surface states may be embedded in deeper layers beneath the topmost surface. Such novel electronic structure presumably related to the modification of crystalline structure during sample cleaving and re-orientation of magnetic moment of Mn atoms near the surface. Mn dopants substituted at the Bi site on the second atomic layer are observed. The ratio of Mn/Bi substitutions is 5%. The electronic structures are fluctuating at atomic scale on the surface, which can affect the magnetism of MnBi2Te4. Our findings shed new lights on the magnetic property of MnBi2Te4 and thus the design of magnetic topological insulators.