Various magnetotransport properties in a high-mobility two-dimensional electron system in strained Si quantum well, were analyzed. The two-flux composite fermion (CF) series of the fractional quantum Hall effect (FQHE), was observed around ν=1/2 at ν=2/3, 3/5, 4/7, and at ν=4/9, 2/5, 1/3. It was observed that of the CF series, the 3/5 state is weaker than the nearby 4/7 state and the 3/7 state is conspicuously missing, which resembles the observation in the integer quantum Hall effect (IQHE) regime that the ν=3 is weaker than the nearby ν=4 state. The results show that at ν=3/5 and 3/7, the twofold valley degeneracy of the CF starts to be lifted and an estimated valley splitting of ∼1 K is obtained.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)