Intrinsic gap of the nu=5/2 fractional quantum Hall state.
The fractional quantum Hall effect is observed at low magnetic field where the cyclotron energy is smaller than the Coulomb interaction energy. The nu=5/2 excitation gap at 2.63 T is measured to be 262+/-15 mK, similar to values obtained in samples with twice the electronic density. Examining the role of disorder on the 5/2 state, we find that a large discrepancy remains between theory and experiment for the intrinsic gap extrapolated from the infinite mobility limit. The observation of a 5/2 state in the low-field regime suggests that inclusion of nonperturbative Landau level mixing may be necessary to fully understand the energetics of half-filled fractional quantum Hall liquids.
Dean
C R
CR
Department of Physics, McGill University, Montreal, H3A 2T8, Canada.
Piot
B A
BA
Hayden
P
P
Das Sarma
S
S
Gervais
G
G
Pfeiffer
L N
LN
West
K W
KW