Unveiling the transport inhomogeneity in magnetic topological insulator MnBi2Te4

It remains highly desirable to achieve a robust quantum anomalous Hall (QAH) state. In this regard, the stoichiometric magnetic topological insulator MnBi2Te4 emerges as a cleaner platform to realize QAH than its magnetically doped counterpart. However, QAH state is scarcely observed in transports in odd-layer MnBi2Te4, calling for a closer examination at the material as well as the device level. Here we employ scanning microwave impedance microscope to address these issues by revealing the transport inhomogeneity at microscopic scale. This transport inhomogeneity manifests as the internal conductive channels due to the structural imperfections, an irregular spatial distribution of chiral edge state and a large spatial variation of materials’ doping level. They all break the picture of a clean QAH state in which a chiral edge state circulates a uniform insulating bulk. Such transport inhomogeneity puts practical constrains on obtaining the quantized transport in the global transport measurements.