Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Higher-order topological insulators in a magnetic field   Two-dimensional (2D) generalization of the Su-Schriffer-Heeger (SSH) model
serves as a platform for exploring higher-order topological insulators (HOTI).
We investigate this model in a magnetic field which interpolates two models
studied so far with zero flux and $\pi$ flux per plaquette. We show that in the
Hofstadter butterfly there appears a wide gap around the $\pi$ flux, which
belongs to the same HOTI discovered by Benalcazar-Bernevig-Hughes (BBH). It
turns out that in a weak field regime HOTI could exist even within a small gap
disconnected from the wider gap around $\pi$ flux. To characterize HOTI, we
employ the entanglement polarization (eP) technique which is useful even if the
basic four bands split into many Landau levels under a magnetic field.

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The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
12
The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
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The categories of this paper are: atom-ph
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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys