Low-Density Spin Susceptibility and Effective Mass of Mobile Electrons in Si Inversion Layers

We studied the Shubnikov–de Haas (SdH) oscillations in high-mobility Si-MOS samples over a wide range of carrier densities $n\simeq (1–50)\times {10}^{11}{\mathrm{cm}}^{-2\mathrm{}}$, 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 ${\chi }^{*}$, the effective mass $m^{*}$, and the $g^{*}$ factor for mobile electrons. These quantities increase gradually with decreasing density; near the 2D MIT, we observed enhancement of ${\chi }^{*}$ by a factor of $\sim 4.7$.