Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anomalous behavior of the Hall effect in electron-doped superconductor
  $Nd_{2-x}$Ce_{x}Cu$O_{4+{\delta}} with nonstoichiometric disorder   Magnetoresistivity and Hall effect measured in magnetic fields up to B=9T
(B||c, J||ab) in electron-doped $Nd_{2-x}$Ce_{x}Cu$O_{4+{\delta}} single
crystal films with x = 0.14; 0.15; 0.18 and different oxygen content ({\delta})
were studied in a temperature range of 0.4-4.2 K. The resistivity and Hall
coefficient behaviors in the mixed state are discussed in the framework of
flux-flow model with the inclusion of the back-flow of vortices owing to the
pinning forces.

9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th