Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Experimental evidence of the dependence of spin tunnelling on the
  concentration of dislocations in Mn12 crystals   We present experimental results on resonant spin tunnelling in a single
crystal of Mn$_{12}$-2Cl benzoate with different concentration of dislocations.
The time evolution of the magnetisation follows the stretched exponential over
a few time decades. The values of parameters of stretched exponential deduced
from experiment have been used to determine the concentration of dislocations
before and after the cooling-annealing process, using the algorithm recently
suggested by Garanin and Chudnovsky.

15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th