Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical orientation of spins in GaAs:Mn/AlGaAs quantum wells via
  impurity-to-band excitation   The paper reports optical orientation experiments performed in the narrow
GaAs/AlGaAs quantum wells doped with Mn. We experimentally demonstrate a
control over the spin polarization by means of the optical orientation via the
impurity-to-band excitation and observe a sign inversion of the luminescence
polarization depending on the pump power. The g factor of a hole localized on
the Mn acceptor in the quantum well was also found to be considerably modified
from its bulk value due to the quantum confinement effect. This finding shows
the importance of the local environment on magnetic properties of the dopants
in semiconductor nanostructures.

33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph