Growth, characterization and Chern insulator state in MnBi$_2$Te$_4$ via the chemical vapor transport method

TL;DR

This study demonstrates the successful growth and characterization of high-quality MnBi$_2$Te$_4$ crystals via chemical vapor transport, revealing enhanced magnetic and electronic properties and observing quantized Hall conductance in thin devices.

Contribution

It introduces a new CVT method for growing MnBi$_2$Te$_4$, resulting in higher quality crystals with improved magnetic and electronic characteristics, enabling observation of quantum phenomena.

Findings

Higher Mn occupancy and antisites in CVT-grown samples

Smaller carrier concentration and Fermi level closer to Dirac point

Highest mobility of 2500 cm$^2$V$^{-1}$s$^{-1}$ with quantized Hall conductance at 1.8 K

Abstract

As the first intrinsic antiferromagnetic topological insulator, MnBi$_2$Te$_4$ has provided a platform to investigate the interplay of band topology and magnetism as well as the emergent phenomena arising from such an interplay. Here we report the chemical-vapor-transport (CVT) growth and characterization of MnBi$_2$Te$_4$, as well as the observation of the field-induced quantized Hall conductance in 6-layer devices. Through comparative studies between our CVT-grown and flux-grown MnBi$_2$Te$_4$ via magnetic, transport, scanning tunneling microscopy, and angle-resolved photoemission spectroscopy measurements, we find that CVT-grown MnBi$_2$Te$_4$ is marked with higher Mn occupancy on the Mn site, slightly higher Mn$_{\rm{Bi}}$ antisites, smaller carrier concentration and a Fermi level closer to the Dirac point. Furthermore, a 6-layer device made from the CVT-grown sample shows by far the highest mobility of 2500 cm$^2$V$\cdot$s in MnBi$_2$Te$_4$ devices with the quantized Hall conductance appearing at 1.8 K and 8 T. Our study provides a new route to obtain high-quality single crystals of MnBi$_2$Te$_4$ that are promising to make superior devices and realize emergent phenomena, such as the layer Hall effect and quantized anomalous hall effect, etc.