We measure the spin polarization (P) of two-dimensional electron gases confined to an InSb quantum well using parallel and tilted magnetic fields. The nonlinear field dependence of P is prominent, leading to a direct deduction of the spin susceptibility ((chi)_(s)) over a wide range of P from 0.07 to 1. (chi)_(s) is found to increase nonlinearly with P and exceed (chi)_(gm) (propor. to) m~(*)g~(*) (where m~(*) and g~(*) are the effective mass and g factor) as commonly used in experiments. We show that (chi)_(s) and (chi)_(gm) obey a square law (chi)_(s)/(chi)_(0) velence ((chi)_(gm)/(chi)_(0))~(2), where (chi)_(0) is the paramagnetic spin susceptibility.
展开▼
