Fractional Quantum Hall Effect in SiGe/Si/SiGe Quantum Wells in Weak Quantizing Magnetic Fields

Abstract

We have experimentally studied the fractional quantum Hall effect (FQHE) in SiGe/Si/SiGe quantum wells in relatively weak magnetic fields, where the Coulomb interaction between electrons exceeds the cyclotron splitting by a factor of a few XX. Minima of the longitudinal resistance have been observed corresponding to the quantum Hall effect of composite fermions with quantum numbers $p$ = 1, 2, 3, and 4. Minima with $p$ = 3 disappear in magnetic fields below 7 Tesla, which may be a consequence of the intersection or even merging of the quantum levels of the composite fermions with different orientations of the pseudo-spin, i.e., those belonging to different valleys. We have also observed minima of the longitudinal resistance at filling factors $\nu$ = 4/5 and 4/11, which may be due to the formation of the second generation of the composite fermions.

References in corpus (6)

• The Two-flux Composite Fermion Series of Fractional Quantum Hall States in Strained Si
• Fractional Quantum Hall Effect at Landau Level Filling nu=4/11
• Strong enhancement of the valley splitting in a 2D electron system in silicon
• Ultra-high mobility two-dimensional electron gas in a SiGe/Si/SiGe quantum well
• Merging of Landau levels in a strongly-interacting two-dimensional electron system in silicon
• Interaction-induced merging of Landau levels in an electron system of double quantum wells

Cited by in corpus (3)

• Quantum phase transition in ultrahigh mobility SiGe/Si/SiGe two-dimensional electron system
• Valley effects on the fractions in an ultrahigh mobility SiGe/Si/SiGe two-dimensional electron system
• Band Flattening and Landau Level Merging in Strongly-Correlated Two-Dimensional Electron Systems