2004/05/19 by K. Lai, Keji Lai, W. Pan +7 · 1 citation
Engineering · Materials Science · Physics and Astronomy · #Advancements in Semiconductor Devices and Circuit Design #Graphene research and applications #Quantum and electron transport phenomena #cond-mat.mes-hall #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.93.156805
published as Phys. Rev. Lett., 93, 156805 (2004) · REVTEX4. 4 pages with 3 postscript figures
arxiv created 2004/05/19 · openalex publication_date 2004/10/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
Magnetotransport properties are investigated in a high-mobility two-dimensional electron system in the strained Si quantum well of a (100) Si0.75Ge0.25/Si/Si0.75Ge0.25 heterostructure, at temperatures down to 30 mK and in magnetic fields up to 45 T. We observe around \ensuremathν=1/2 the two-flux composite fermion (CF) series of the fractional quantum Hall effect (FQHE) at \ensuremathν=2/3, 3/5, 4/7, and at \ensuremathν=4/9,2/5,1/3. Among these FQHE states, the \ensuremathν=1/3,4/7, and 4/9 states are seen for the first time in the Si/SiGe system. Interestingly, of the CF series, the 3/5 state is weaker than the nearby 4/7 state and the 3/7 state is conspicuously missing, resembling the observation in the IQHE regime that the \ensuremathν=3 is weaker than the nearby \ensuremathν=4 state. Our results can be quantitatively understood in the picture of CF's with the valley degree of freedom.