Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effect of fluctuations on vortex lattice structural transitions in
  superconductors   The rhombic-to-square transition field $H_{\Box}(T)$ for cubic and tetragonal
materials in fields along [001] is evaluated using the nonlocal London theory
with account of thermal vortex fluctuations. Unlike extended Ginzburg-Landau
models, our approach shows that the line $H_{\Box}(T)$ and the upper critical
field $H_{c2}(T)$ do not cross due to strong fluctuations near $H_{c2}(T)$
which suppress the square anisotropy induced by the nonlocality. In increasing
fields, this causes re-entrance of the rhombic structure in agreement with
recent neutron scattering data on borocarbides.

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The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
3
The categories of this paper are: physics
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th