MnBi2Te4 (MBT) materials are promising antiferromagnetic topological insulators where field driven ferromagnetism is predicted to cause a transition between axion insulator and Weyl 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 trivial 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~∼~60 Tesla. As a consequence, the low-field magnetization plateau state in MBT, where many determinations of quantum anomalous Hall state are studied, actually consists of ferrimagnetic septuple blocks containing both a uniform and staggered magnetization component.
@article{arxiv.2102.05797,
title = {Defect-driven ferrimagnetism and hidden magnetization in MnBi$_2$Te$_4$},
author = {You Lai and Liqin Ke and Jiaqiang Yan and Ross D. McDonald and Robert J. McQueeney},
journal= {arXiv preprint arXiv:2102.05797},
year = {2021}
}