Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magnetophonon resonance in high density, high mobility quantum well
  systems   We have investigated the magnetophonon resonance (MPR) effect in a series of
single GaAs quantum well samples which are symmetrically modulation doped in
the adjacent short period AlAs/GaAs superlattices. Two distinct MPR series are
observed originating from the $\Gamma$ and X electrons interacting with the
GaAs and AlAs longitudinal optic (LO) phonons respectively. This confirms
unequivocally the presence of X electrons in the AlAs quantum well of the
superlattice previously invoked to explain the high electron mobility in these
structures (Friedland et al. Phys. Rev. Lett. 77,4616 (1996).

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The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas