THE TWO-FLUX COMPOSITE FERMION SERIES OF FRACTIONAL QUANTUM HALL STATES IN STRAINED (100) Si

摘要

Magnetotransport properties are studied in a high-mobility 2DES in the strained Si quantum well. We observe around ν = 1/2 the two-flux composite fermion (CF~2) series of the FQHE states at ν = 2/3, 3/5, 4/7, and at ν = 4/9, 2/5, 1/3. Of the CF series, the ν = 3/5 state is weaker than the nearby 4/7 state and the 3/7 state is missing, resembling the observation that the ν = 3 is weaker than the ν = 4 state. Our data indicate that the CF model still applies for the multivalley Si/SiGe system when taking into account the two-fold valley degeneracy.