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<or=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<or=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<or=nu<0.85 the 2DES remains partially polarized for the broad range of magnetic fields from 2.75 to 11 T. This is consistent with the presence of a mixture of polarized and depolarized regions.
Groshaus
J G
JG
Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel and Bell Laboratories, Lucent Technology, Murray Hill, New Jersey 07974, USA.
Plochocka-Polack
P
P
Rappaport
M
M
Umansky
V
V
Bar-Joseph
I
I
Dennis
B S
BS
Pfeiffer
L N
LN
West
K W
KW
Gallais
Y
Y
Pinczuk
A
A