2 research outputs found
The Fermi edge singularity of spin polarized electrons
We study the absorption spectrum of a two-dimensional electron gas (2DEG) in
a magnetic field. We find that that at low temperatures, when the 2DEG is spin
polarized, the absorption spectra, which correspond to the creation of spin up
or spin down electron, differ in magnitude, linewidth and filling factor
dependence. We show that these differences can be explained as resulting from
creation of a Mahan exciton in one case, and of a power law Fermi edge
singularity in the other.Comment: 4 pages, 4 figures, published in Phys. Rev. Let
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.Comment: 4 pages, 4 figures (Fig 4 is in color