Valley splitting of Si/SiGe heterostructures in tilted magnetic fields

Lai, K.; Lu, T. M.; Pan, W.; Tsui, D. C.; Lyon, S.; Liu, J.; Xie, Y. H.; Muhlberger, M.; Schaffler, F.

Valley splitting of Si/SiGe heterostructures in tilted magnetic fields

Authors

Description

We have investigated the valley splitting of two-dimensional electrons in high quality Si/Si$_{1-x}$Ge$_x$ heterostructures under tilted magnetic fields. For all the samples in our study, the valley splitting at filling factor $ν=3$ ($Δ_3$) is significantly different before and after the coincidence angle, at which energy levels cross at the Fermi level. On both sides of the coincidence, a linear density dependence of $Δ_3$ on the electron density was observed, while the slope of these two configurations differs by more than a factor of two. We argue that screening of the Coulomb interaction from the low-lying filled levels, which also explains the observed spin-dependent resistivity, is responsible for the large difference of $Δ_3$ before and after the coincidence.
REVTEX 4 pages, 4 figures