The recent realizations of the quantum anomalous Hall effect (QAHE) in MnBi2Te4 and MnBi4Te7 benchmark the (MnBi2Te4)(Bi2Te3)n family as a promising hotbed for further QAHE improvements. The family owes its potential to its ferromagnetically (FM) ordered MnBi2Te4 septuple layers (SL). However, the QAHE realization is complicated in MnBi2Te4 and MnBi4Te7 due to the substantial antiferromagnetic (AFM) coupling between the SL. An FM state, advantageous for the QAHE, can be stabilized by interlacing the SL with an increasing number n of Bi2Te3 layers. However, the mechanisms driving the FM state and the number of necessary QLs are not understood, and the surface magnetism remains obscure. Here, we demonstrate robust FM properties in MnBi6Te10 (n=2) with TC≈12 K and establish their origin in the Mn/Bi intermixing phenomenon by a combined experimental and theoretical study. Our measurements reveal a magnetically intact surface with a large magnetic moment, and with FM properties similar to the bulk. Our investigation thus consolidates the MnBi6Te10 system as perspective for the QAHE at elevated temperatures.
@article{arxiv.2302.01023,
title = {Intermixing-driven surface and bulk ferromagnetism in the quantum anomalous Hall candidate MnBi$_6$Te$_{10}$},
author = {Abdul V. Tcakaev and Bastian Rubrecht and Jorge I. Facio and Volodymyr B. Zabolotnyy and Laura T. Corredor and Laura C. Folkers and Ekaterina Kochetkova and Thiago R. F. Peixoto and Philipp Kagerer and Simon Heinze and Hendrik Bentmann and Robert J. Green and Pierluigi Gargiani and Manuel Valvidares and Eugen Weschke and Maurits W. Haverkort and Friedrich Reinert and Jeroen van den Brink and Bernd Büchner and Anja U. B. Wolter and Anna Isaeva and Vladimir Hinkov},
journal= {arXiv preprint arXiv:2302.01023},
year = {2023}
}