Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Granularity and vortex dynamics in LaO_0.92F_0.08FeAs as probed by
  harmonics of the AC magnetic susceptibility   Fundamental and higher harmonics of the AC magnetic susceptibility have been
measured on a LaO_0.92F_0.08FeAs sample as a function of the temperature, at
various amplitudes and frequencies of the AC magnetic field, with a small
superimposed DC field parallel to the AC field. The granularity of the sample
has been investigated and the inter-grain and intra-grain contributions have
been clearly individuated looking at both the first and third harmonics. The
vortex dynamics has been also analyzed, and a comparison with the magnetic
behavior of both the MgB_2 and the cuprate superconductors has been performed.
Some vortex dissipative phenomena, i.e. the thermally activated flux flow and
the flux creep, have been detected in the presented measurements, similar to
what obtained on YBCO. Nevertheless, although the general behavior is similar,
several differences have been also evidenced between these different classes of
superconductors, mainly in the third harmonics. We infer that different vortex
dynamics have to be included into the analysis of the magnetic response in this
iron-based new material.

3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con