Defect-driven ferrimagnetism and hidden magnetization in MnBi2Te4

MnBi2Te4 (MBT) materials are promising antiferromagnetic topological insulators in which field-driven ferromagnetism is predicted to cause a transition between axion insulator andWeyl semimetallic states. However, the presence of antiferromagnetic coupling between Mn/Bi antisite defects and the main Mn layer can reduce the low-field magnetization, and it has been shown that such defects are more prevalent in the structurally identical magnetic insulator MnSb2Te4 (MST). We use high-field magnetization measurements to show that the magnetization of MBT and MST occur in stages and full saturation requires fields of similar to 60 T. As a consequence, the low-field magnetization plateau state in MBT, where many determinations of the quantum anomalous Hall state are studied, actually consists of ferrimagnetic septuple blocks containing both uniform and staggered magnetization components.

Automated summary

The magnetization of MnBi2Te4 (MBT) and MnSb2Te4 (MST) occurs in stages and full saturation requires fields of around 60 T. The low-field magnetization plateau state in MBT actually consists of ferrimagnetic septuple blocks containing both uniform and staggered magnetization components.