Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Absorption in the fractional quantum Hall regime: trion dichroism and
  spin polarization   We present measurements of optical interband absorption in the fractional
quantum Hall regime in a GaAs quantum well in the range 0 < nu < 1. We
investigate the mechanism of singlet trion absorption, and show that its
circular dichroism can be used as a probe of the spin polarization of the
ground state of the two-dimensional electron system (2DES). We find that at nu
= 1/3 the 2DES is fully spin-polarized. Increasing the filling factor results
in a gradual depolarization, with a sharp minimum in the dichroism near nu =
2/3. We find that in the range 0.5 < nu < 0.85 the 2DES remains partially
polarized for the broad range of magnetic fields from 2.75 to 11 Tesla. This is
consistent with the presence of a mixture of polarized and depolarized regions.

23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th