Abstract
We study a two-dimensional electron system where the electrons occupy two conduction band valleys with anisotropic Fermi contours and strain-tunable occupation. We observe persistent quantum Hall states at filling factors ν=1/3 and 5/3 even at zero strain when the two valleys are degenerate. This is reminiscent of the quantum Hall ferromagnet formed at ν=1 in the same system at zero strain. In the absence of a theory for a system with anisotropic valleys, we compare the energy gaps measured at ν=1/3 and 5/3 to the available theory developed for single-valley, two-spin systems, and find that the gaps and their rates of rise with strain are much smaller than predicted.
Original language | English (US) |
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Article number | 016805 |
Journal | Physical review letters |
Volume | 104 |
Issue number | 1 |
DOIs | |
State | Published - Jan 7 2010 |
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)