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

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${}_{\mathrm{Bi}}$ 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.

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