We determine the energy splitting of the conduction-band valleys in two-dimensional electrons confined to low-disorder Si quantum wells. We probe the valley splitting dependence on both perpendicular magnetic field B and Hall density by performing activation energy measurements in the quantum Hall regime over a large range of filling factors. The mobility gap of the valley-split levels increases linearly with B and is strikingly independent of Hall density. The data are consistent with a transport model in which valley splitting depends on the incremental changes in density eB/h across quantum Hall edge strips, rather than the bulk density. Based on these results, we estimate that the valley splitting increases with density at a rate of 116 μeV/1011cm−2, consistent with theoretical predictions for near-perfect quantum well top interfaces.
@article{arxiv.2006.02305,
title = {Effect of quantum Hall edge strips on valley splitting in silicon quantum wells},
author = {Brian Paquelet Wuetz and Merritt P. Losert and Alberto Tosato and Mario Lodari and Peter L. Bavdaz and Lucas Stehouwer and Payam Amin and James S. Clarke and Susan N. Coppersmith and Amir Sammak and Menno Veldhorst and Mark Friesen and Giordano Scappucci},
journal= {arXiv preprint arXiv:2006.02305},
year = {2020}
}