In high-quality two-dimensional electrons confined to GaAs quantum wells, near Landau level filling factors ν=1/2 and 1/4, we observe signatures of the commensurability of the electron-flux composite fermion cyclotron orbits with a unidirectional periodic density modulation. Focusing on the data near ν=1/2, we directly and quantitatively probe the shape of the composite fermions' cyclotron orbit, and therefore their Fermi contour, as a function of magnetic field (B) applied parallel to the sample plane. The composite fermion Fermi contour becomes severely distorted with increasing B and appears to be elliptical, in sharp contrast to the electron Fermi contour which splits as the system becomes bilayerlike at high B. We present a simple, qualitative model to interpret our findings.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Feb 11 2014|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics