Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Valley-momentum locking in a graphene superlattice with Y-shaped
  Kekul\'e bond texture   Recent experiments by Guti\'errez $\textit{et al.}$ [Nature Phys.
$\textbf{12}$, 950 (2016)] on a graphene-copper superlattice have revealed an
unusual Kekul\'e bond texture in the honeycomb lattice --- a Y-shaped
modulation of weak and strong bonds with a wave vector connecting two Dirac
points. We show that this so-called "Kek-Y" texture produces two species of
massless Dirac fermions, with valley isospin locked parallel or antiparallel to
the direction of motion. In a magnetic field $B$ the valley degeneracy of the
$B$-dependent Landau levels is removed by the valley-momentum locking --- but a
$B$-independent and valley-degenerate zero-mode remains.

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The categories of this paper are: cs
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The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
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The categories of this paper are: astro-ph
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The categories of this paper are: math
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The categories of this paper are: quant-ph
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga