Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Temperature-induced spontaneous time-reversal symmetry breaking on the
  honeycomb lattice   Phase transitions involving spontaneous time-reversal symmetry breaking are
studied on the honeycomb lattice at finite hole-doping with
next-nearest-neighbor repulsion. We derive an exact expression for the
mean-field equation of state in closed form, valid at temperatures much less
than the Fermi energy. Contrary to standard expectations, we find that
thermally induced intraband particle-hole excitations can create and stabilize
a uniform metallic phase with broken time-reversal symmetry as the temperature
is "raised" in a region where the groundstate is a trivial metal.

17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex