Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic field distribution and characteristic fields of the vortex
  lattice for a clean superconducting niobium sample in an external field
  applied along a three-fold axis   The field distribution in the vortex lattice of a pure niobium single crystal
with an external field applied along a three-fold axis has been investigated by
the transverse-field muon-spin-rotation (TF-$\mu$SR) technique over a wide
range of temperatures and fields. The experimental data have been analyzed with
the Delrieu's solution for the form factor supplemented by phenomenological
formulas for the parameters. This has enabled us to experimentally establish
the temperatures and fields for the Delrieu's, Ginzburg-Landau's, and Klein's
regions of the vortex lattice. Using the numerical solution of the
quasiclassical Eilenberger's equation the experimental results have been
reasonably understood. They should apply to all clean BCS superconductors. The
analytical Delrieu's model supplemented by phenomenological formulas for its
parameters is found to be reliable for analyzing TF-$\mu$SR experimental data
for a substantial part of the mixed phase. The Abrikosov's limit is contained
in it.

27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con