NETWORK MODEL FOR A 2-DIMENSIONAL DISORDERED ELECTRON-SYSTEM WITH SPIN-ORBIT SCATTERING

introduce a network model to describe two-dimensional disordered elect ron systems with spin-orbit scattering. The network model is defined b y a discrete unitary time-evolution operator. We establish by numerica l transfer matrix calculations that the model exhibits a localization- delocalization transition. We determine the corresponding phase diagra m in the parameter space of disorder scattering strength and spinorbit scattering strength. Near the critical point we determine by statisti cal analysis a one-parameter scaling function and the critical exponen t of the localization length to be nu = 2.51 +/- 0.18. Based on a conf ormal mapping we also calculate the scaling exponent of the typical lo cal density of states alpha(0) = 2.174 +/- 0.003.