Low-temperature magnetization studies of nb^xsii-^x. Films

We have measured the magnetization of thick films as a function of temperature (T) and magnetic field (H) near the metal-insulator (MI) transition. In the insulating phase the susceptibility x K T with a = 0.8 and both the T- and the //-dependence of X are well described by a hierarchical spin-pairing model. In the metallic phase x shows a similar power-law behavior with a « 0.55, indicative of non-Fermi liquid behavior. We compare these results with similar measurements in doped semiconductors and with existing theories of the disordered insulating and metallic phases. The data suggest a decoupling of transport and magnetic behavior at the MI transition.