Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetic refrigeration with paramagnetic semiconductors at cryogenic
  temperatures   We propose paramagnetic semiconductors as active media for refrigeration at
cryogenic temperatures by adiabatic demagnetization. The paramagnetism of
impurity dopants or structural defects can provide the entropy necessary for
refrigeration at cryogenic temperatures. We present a simple model for the
theoretical limitations to specific entropy and cooling power achievable by
demagnetization of various semiconductor systems. Performance comparable to
that of the hydrate (CMN) is predicted.

36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys