In an AlAs quantum well where two-dimensional electrons occupy two conduction-band valleys with anisotropic Fermi contours, we tune the valley splitting energy via the application of strain and measure the energy gaps for the quantum-Hall state at filling factor ν=1. At zero valley splitting energy (strain), there is a sizeable energy gap which increases linearly with density. At a fixed density, the gap rises with increasing strain much faster than the single-particle picture predicts. Interpreting the rapid rise of the gap as a signature of valley Skyrmions, we find that their size grows as the electron density increases.
|Physical Review B - Condensed Matter and Materials Physics
|Published - Mar 31 2010
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics