Theory of Oscillatory g Factor in an MOS Inversion Layer under Strong Magnetic Fields

The oscillatory enhancement of the g factor caused by the exchange interaction among electrons is calculated. The degree of the spin splitting of each Landau level observed in Schubnikov-de Haas oscillation is shown to be explained by the theory of the level broadening of Landau levels if such enhancement is taken into account. The g factor is also calculated under tilted magnetic fields, and the theoretical one is in excellent agreement with the experiment by Fang and Stiles, and with the similar one performed recently by Kobayashi and Komatsubara. It is proposed that the valley splitting is enhanced by just the same mechanism and that such enhancement is a possible reason why it is observed experimentally in low-lying Landau levels.