Publications
Valley splitting of Si/Si1-xGex heterostructures in tilted magnetic fields
We have investigated the valley splitting of two-dimensional electrons in high-quality Si/Si{sub 1-x}Ge{sub x} heterostructures under tilted magnetic fields. For all the samples in our study, the valley splitting at filling factor {nu} = 3 ({Delta}{sub 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 dependence of {Delta}{sub 3} on the electron density was observed, while the slope of these two configurations differs by more than a factor of 2. 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 {Delta}{sub 3} before and after the coincidence.