On the Magnetoresistance Maximum Observed in the Intermediate Magnetic Field Region for the Two-Dimensional Hole Gas in a Strained Si0.05Ge0.95 Quantum Well

The magnetoresistance (MR) of a two-dimensional hole gas in a quantum well of compressively strained Si0.05Ge0.95 has been investigated as a function of temperature. The MR shows a maximum at intermediate magnetic fields between the regions of weak localization and the Shubnikov-de Haas oscillations, which is discussed in terms of a recent theoretical study of the electron-electron interaction effect by Sedrakyan and Raikh (SR). The magnetic field MR dependence is clearly observed to cross over from quadratic to linear at T=7.8 K and B≈0.3 T. It is shown that the SR theory provides a good description of both the measured quadratic and positive linear MR, but over estimates the field position of the MR maximum and does not account for the shift in position with temperature that is observed. Earlier theories of electron-electron interaction (by Altshuler and Aronov, Gornyi and Mirlin) show a better agreement with the experimentally observed behavior of the MR maximum, but fit the low field MR less accurately.