The low-density spin susceptibility and effective mass of mobile electrons in Si inversion layers

Abstract

We studied the Shubnikov-de Haas (SdH) oscillations in high-mobility Si-MOS samples over a wide range of carrier densities $n\simeq (1-50)\times 10^{11}$cm${}^{-2}$, which includes the vicinity of the apparent metal-insulator transition in two dimensions (2D MIT). Using a novel technique of measuring the SdH oscillations in superimposed and independently controlled parallel and perpendicular magnetic fields, we determined the spin susceptibility $\ddot{I}{‡}^{\ast }$, the effective mass $m^{\ast }$, and the $g^{\ast }$-factor for mobile electrons. These quantities increase gradually with decreasing density; near the 2D MIT, we observed enhancement of $\ddot{I}{‡}^{\ast }$ by a factor of $\sim 4.7$.

4 pages, 4 figures