Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Landau levels and shallow donor states in GaAs/AlGaAs multiple quantum
  wells at mega-gauss magnetic fields   Landau levels and shallow donor states in multiple GaAs/AlGaAs quantum wells
(MQWs) are investigated by means of the cyclotron resonance at mega-gauss
magnetic fields. Measurements of magneto-optical transitions were performed in
pulsed fields up to 140 T and temperatures from 6 to 300 K. The $14\times14$
\textbf{P}$\cdot$\textbf{p} band model for GaAs is used to interpret
free-electron transitions in a magnetic field. Temperature behavior of the
observed resonant structure indicates, in addition to the free-electron Landau
states, contributions of magneto-donor states in the GaAs wells and possibly in
the AlGaAs barriers. The magneto-donor energies are calculated using a
variational procedure suitable for high magnetic fields and accounting for
conduction band nonparabolicity in GaAs. It is shown that the above states,
including their spin splitting, allow one to interpret the observed
magneto-optical transitions in MQWs in the middle infrared region. Our
experimental and theoretical results at very high magnetic fields are
consistent with the picture used previously for GaAs/AlGaAs MQWs at lower
magnetic fields.

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The categories of this paper are: cs
23
The categories of this paper are: solv-int
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The categories of this paper are: hep-th
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
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The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
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The categories of this paper are: stat
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The categories of this paper are: acc-phys
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The categories of this paper are: math
33
The categories of this paper are: plasm-ph