NMR determination of 2D electron spin polarization at nu = 1/2
Using a "standard" NMR spin-echo technique we determined the spin polarization P of two-dimensional electrons, confined to GaAs quantum wells, from the hyperfine shift of Ga nuclei located in the wells. Concentrating on the temperature ( 0.05 less, similarT less, similar10 K) and magnetic field ( 7 less, similarB less, similar17 T) dependencies of P at Landau level filling factor nu = 1/2, we find that the results are described well by a simple model of noninteracting composite fermions, although some inconsistencies remain when the two-dimensional electron system is tilted in the magnetic field.
Melinte
S
Unite PCPM, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium.
Freytag
N
Horvatic
M
Berthier
C
Levy
LP
Bayot
V
Shayegan
M