Magnetoresistance in Dilute $p$-Si/SiGe in Parallel and Tilted Magnetic Fields

Abstract

We report the results of an experimental study of the magnetoresistance $\rho_{xx}$ and $\rho_{xy}$ in two samples of $p$-Si/SiGe with low carrier concentrations $p$=8.2$\times10^{10}$ cm$^{-2}$ and $p$=2$\times10^{11}$ cm$^{-2}$. The research was performed in the temperature range of 0.3-2 K and in the magnetic fields of up to 18 T, parallel or tilted with respect to the two-dimensional (2D) channel plane. The large in-plane magnetoresistance can be explained by the influence of the \textit{in-plane} magnetic field on the orbital motion of the charge carriers in the quasi-2D system. The measurements of $\rho_{xx}$ and $\rho_{xy}$ in the tilted magnetic field showed that the anomaly in $\rho_{xx}$, observed at filling factor $\nu$=3/2 is practically nonexistent in the conductivity $\sigma_{xx}$. The anomaly in $\sigma_{xx}$ at $\nu$=2 might be explained by overlapping of the levels with different spins 0$\uparrow$ and 1$\downarrow$ when the tilt angle of the applied magnetic field is changed. The dependence of g-factor $g^*(\Theta)/g^*(0^0)$ on the tilt angle $\Theta$ was determined.