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Valley splitting of Si/SiGe heterostructures in tilted magnetic fields

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

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.

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K. Lai, T. M. Lu, W. Pan, D. C. Tsui, S. Lyon, J. Liu, Y. H. Xie, M. Muhlberger, F. Schaffler. 2006-01-27. Valley splitting of Si/SiGe heterostructures in tilted magnetic fields. https://doi.org/10.1103/physrevb.73.161301

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