Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reentrant superconductivity in a strong applied field within the
  tight-binding model   It was suggested by Rasolt and Te\v{s}anovi\'c that the Landau level
quantization in isotropic superconductors could enhance superconductivity in a
very strong magnetic field, above the upper critical field ($H_{c2}$). We
derive a generalized Harper equation for superconducting systems, and show that
a similar reentrant behavior appears in a lattice model, even though the
Landau--level--structure is destroyed by the periodic potential in that case.
Both the orbital and the Zeeman field--induced effects are taken into account.

25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con