Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superconducting phase transition of Sr2RuO4 in magnetic field   The superconducting state formed due to direct intra-orbital pairing in
tetragonal multi-band superconductor Sr$_2$RuO$_4$ has different properties
than the state formed due to intra-band pairing. In particular, the theory
operating with direct intra-orbital pairing successfully explains the Kerr
rotation of reflected light polarization observed several years ago. Here we
apply intra-orbital approach to the problem of Ginzburg-Landau description of
basal plane upper critical field in this material. It is shown that typical for
two component superconducting state additional phase transition in the vortex
state at $H<H_{c2}$ for all four crystallographic directions of magnetic field
in the basal plane and the basal plane upper critical field anisotropy still
are inevitable properties even in case of direct intra-orbital pairing.

14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an