Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Diamagnetism of 2D-Fermions in the Strong Nonhomogeneous Static Magnetic
  Field $( {\bf B} =B( 0, 0, 1/cosh^{2}( \frac{x-x_{0} }{ \delta })))$ : gas
  magnetization, ... and gas compressibility   We study diamagnetism of a gas of fermions moving in a nonhomogeneous
magnetic field $( {\bf B} =B( 0, 0, 1/cosh^{2}( \frac{x-x_{0} }{ \delta })))$
The gas magnetization, the static magnetic susceptibility, the chemical
potential and the gas compressibility are discussed and compared with the
uniform field case. General need to study dynamics of electrons in different
types of magnetic fields follows from a large number of experimental situations
in which its understanding enables physicists to obtain new information.

27
The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph