Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hyperfine interactions in two-dimensional HgTe topological insulators   We study the hyperfine interaction between the nuclear spins and the
electrons in a HgTe quantum well, which is the prime experimentally realized
example of a two-dimensional topological insulator. The hyperfine interaction
is a naturally present, internal source of broken time-reversal symmetry from
the point of view of the electrons. The HgTe quantum well is described by the
so-called Bernevig-Hughes-Zhang (BHZ) model. The basis states of the BHZ model
are combinations of both S- and P-like symmetry states, which means that three
kinds of hyperfine interactions play a role: (i) The Fermi contact interaction,
(ii) the dipole-dipole like coupling and (iii) the electron orbital to
nuclear-spin coupling. We provide benchmark results for the forms and
magnitudes of these hyperfine interactions within the BHZ model, which give a
good starting point for evaluating hyperfine interactions in any HgTe
nanostructure. We apply our results to the helical edge states of a HgTe
two-dimensional topological insulator and show how their total hyperfine
interaction becomes anisotropic and dependent on the orientation of the sample
edge within the plane. Moreover, for the helical edge states the hyperfine
interactions due to the P-like states can dominate over the S-like contribution
in certain circumstances.

6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
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The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys