The domain structure of a MnSb2Te4 single crystal with a Curie temperature TC≈45K was studied using the high-resolution Bitter decoration technique. Magnetotransport measurements confirm a soft ferromagnetic ordering with a coercive field of ∼100 Oe. We revealed the formation of a hierarchical domain structure characterized by two distinct spatial scales. These results indicate the existence of two magnetically weakly coupled subsystems -- surface and bulk. The observed sub-domain structure can be attributed to the formation of a ferromagnetic well due to an inhomogeneous distribution of MnSb antisite defects, with an additional contribution from symmetry breaking in the near-surface layer.
@article{arxiv.2601.12399,
title = {Sub-domain structure in a single crystal of the magnetic topological insulator MnSb2Te4},
author = {V. A. Tyutvinov and M. S. Sidelnikov and N. A. Abdullayev and Z. S. Aliev and I. R. Amiraslanov and N. T. Mamedov and V. N. Zverev and L. Ya. Vinnikov},
journal= {arXiv preprint arXiv:2601.12399},
year = {2026}
}