Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Negative Magnetoresistance of Granular Metals in a Strong Magnetic Field   The magnetoresistance of a granular superconductor in a strong magnetic field
destroying the gap in each grain is considered. It is assumed that the
tunneling between grains is sufficiently large such that all conventional
effects of localization can be neglected. A non-trivial sensitivity to the
magnetic field comes from superconducting fluctuations leading to the formation
of virtual Cooper pairs and reducing the density of states. At low temperature,
the pairs do not contribute to the macroscopic transport but their existence
can drastically reduce the conductivity. Growing the magnetic field one
destroys the fluctuations, which improves the metallic properties and leads to
the negative magnetoresistance.

24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph