Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Topological surface states of MnBi$_2$Te$_4$ at finite temperatures and
  at domain walls   MnBi$_2$Te$_4$ has recently been the subject of intensive study, due to the
prediction of axion insulator, Weyl semimetal, and quantum anomalous Hall
insulator phases, depending on the structure and magnetic ordering.
Experimental results have confirmed some aspects of this picture, but several
experiments have seen zero-gap surfaces states at low temperature, in conflict
with expectations. In this work, we develop a first-principles-based
tight-binding model that allows for arbitrary control of the local spin
direction and spin-orbit coupling, enabling us to accurately treat large
unit-cells. Using this model, we examine the behavior of the topological
surface state as a function of temperature, finding a gap closure only above
the N\'eel temperature. In addition, we examine the effect of magnetic domains
on the electronic structure, and we find that the domain wall zero-gap states
extend over many unit-cells. These domain wall states can appear similar to the
high temperature topological surface state when many domain sizes are averaged,
potentially reconciling theoretical results with experiments.

31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th