Dependence of spin susceptibility of a two-dimensional electron system on the valley degree of freedom

The dependence of spin susceptibility of a two-dimensional electron system (2DES) was investigated on the valley degree of freedom. The samples contained 2D electrons confined to a modulation doped, 11 nm-wide, AlAs quantum well grown on a GaAs (001) substrate using molecular beam epitaxy. The 2DES could be varied using metal electrodes deposited on the front and back sides of the samples and illumination. The results show that a two-valley two-dimensional system is effectively more dilute than a single-valley system because of its smaller Fermi energy.