Transport properties of thin flakes of the antiferromagnetic topological insulator MnBi2Te4

Abstract

$\mathrm{MnB}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{4}$ was recently suggested as the first example of an antiferromagnetic topological insulator. However, lacking good quality of single crystals hindered its further investigation. Here, we report the detailed transport properties of several $\mathrm{MnB}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{4}$ thin flakes in which samples are more homogeneous as compared to the bulk single crystals. We found all the samples exhibit antiferromagnetic transition around 25 K and the same field-driven magnetic transitions; however, temperature dependence of resistivities shows either insulating or metallic behaviors. Such behavior is in contrast with the as-grown thick single crystals in which only metallic behavior was observed. The Hall coefficients indicate the gradual decrease of the carrier density with decreasing the temperature for the sample with insulating behavior. Such difference may relate to different impurity content (antisite defects and/or Mn vacancies). Our findings indicate the bulk carrier can be localized at low temperature by introducing disorder while the magnetic ordering keeps invariant, which is quite crucial for realizing the theoretical proposed quantum anomalous Hall effect and axion insulators in this material.