Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Four-fold anisotropy of the parallel upper critical magnetic field in a
  pure layered d-wave superconductor at $T = 0$   It is well known that a four-fold symmetry of the parallel upper critical
magnetic field disappears in the Ginzburg-Landau (GL) region in
quasi-two-dimensional (Q2D) $d$-wave superconductors. Therefore, it has been
accurately calculated so far as a correction to the GL results, which is valid
close to superconducting transition temperature and is expected to be stronger
at low temperatures. As to the case $T=0$, some approximated methods have been
used, which are good only for closed electron orbits and unappropriate for the
open orbits which exist in a parallel magnetic field in Q2D superconductors.
For the first time, we accurately calculate the four-fold anisotropy of the
parallel upper critical magnetic field in a pure Q2D $d$-wave superconductor at
$T=0$, where it has the highest possible value. Our results are applicable to
Q2D $d$-wave high-Tc and organic superconductors.

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The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci