Abstract
Magnetotransport properties are investigated in a high-mobility two-dimensional electron system in the strained Si quantum well of a (100) heterostructure, at temperatures down to 30 mK and in magnetic fields up to 45 T. We observe around the two-flux composite fermion (CF) series of the fractional quantum Hall effect (FQHE) at , and at . Among these FQHE states, the , and states are seen for the first time in the system. Interestingly, of the CF series, the state is weaker than the nearby state and the state is conspicuously missing, resembling the observation in the IQHE regime that the is weaker than the nearby state. Our results can be quantitatively understood in the picture of CF's with the valley degree of freedom.
- Received 5 March 2004
DOI:https://doi.org/10.1103/PhysRevLett.93.156805
©2004 American Physical Society