Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The level shifting induced negative magnetoresistance in the
  nearest-neighbor hopping conduction   We propose a new mechanism of negative magnetoresistance in non-magnetic
granular materials in which electron transport is dominated by hopping between
two nearest-neighbor clusters. We study the dependence of magnetoresistance on
temperature and separation between neighboring clusters. At a small separation
we find a negative magnetoresistance at low temperatures and it changes over to
a positive value as temperature increases. For a fixed temperature,
magnetoresistance changes from negative to positive when the cluster separation
increases. The change of magnetoresistance $\Delta R/R$ can be more than 80% at
low temperatures.

21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg