Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Self-organized criticality induced by quenched disorder: experiments on
  flux avalanches in NbH$_x$ films   We present an experimental study of the influence of quenched disorder on the
distribution of flux avalanches in type-II superconductors. In the presence of
much quenched disorder, the avalanche sizes are power-law distributed and show
finite size scaling, as expected from self-organized criticality (SOC).
Furthermore, the shape of the avalanches is observed to be fractal. In the
absence of quenched disorder, a preferred size of avalanches is observed and
avalanches are smooth. These observations indicate that a certain minimum
amount of disorder is necessary for SOC behavior. We relate these findings to
the appearance or non-appearance of SOC in other experimental systems,
particularly piles of sand.

27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph