Effect of valley degeneracy on spin susceptibility of a two-dimensional quantum electron liquid

We investigate theoretically the effect of valley degeneracy on the spin susceptibility of a two-dimensional quantum electron liquid by determining the spin-polarization dependence of the ground-state energy within the selfconsistent mean-field approximation of Singwi et al. Specifically, we have studied a two valley system as realized in the Si (100) inversion layer. In qualitative agreement with the recent quantum Monte Carlo study by Marchi et al., we find that the valley degeneracy results in suppression of spin susceptibility over the single valley case. However, the quality of agreement diminishes with increasing value of the coupling parameter rs. This indicates the limitation of mean-field theory to deal with the exchange-correlation effects in the strong coupling region. But, our results show considerable improvement over the random-phase approximation which ignores these correlations completely