Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Graphite, graphene and the flat band superconductivity   Superconductivity with transition temperature $T_c=1.7$ K has been reported
in bilayer graphene [1,2]. The main factors, which may shed light on the
mechanism of the formation of this superconductivity, are the following.
Superconductivity is observed in bilayer graphene, when the two layers are
twisted, and the maximum of $T_c$ takes place at the "magic angle" of twist, at
which the electronic band structure becomes nearly flat. The same factors have
been suggested [3] to explain the experiments in graphite [4-8], which reported
high-T superconductivity in highly oriented pyrolytic graphite (HOPG). The
hints of room-T superconductivity are present, only when the sample contains
quasi two-dimensional interfaces between the domains of HOPG. These domains
should be twisted with respect to each other in order to form the flat band in
electronic spectrum. This dispersionless energy spectrum has a singular density
of states, which provides the transition temperature being proportional to the
coupling constant instead of the exponential suppression. The graphite and its
superconductivity is now becoming the mainstream. One may say that we are
coming to graphite era of superconductivity. It is time to combine the
theoretical and experimental efforts to reach the bulk room-T superconductivity
in graphite and in similar real or artificial materials.

2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess