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arXiv · 1001.1290

Ferromagnetic Fractional Quantum Hall States in a Valley-Degenerate Two-Dimensional Electron System

Medini Padmanabhan·T. Gokmen·M. Shayegan
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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.

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Medini Padmanabhan, T. Gokmen, M. Shayegan. 2010-01-07. Ferromagnetic Fractional Quantum Hall States in a Valley-Degenerate Two-Dimensional Electron System. https://doi.org/10.1103/physrevlett.104.016805

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