LOW-TEMPERATURE MAGNETIZATION STUDIES OF NBXSI1-X FILMS

We have measured the magnetization of thick NbxSi1-x films as a function of temperature (T) and magnetic field (H) near the metal-insulator (MI) transition. In the insulating phase the susceptibility chi is-proportional-to T(-alpha) with alpha almost-equal-to 0.8 and both the T- and the H-dependence of chi are well described by a hierarchical spin-pairing model. In the metallic phase chi shows a similar power-law behavior with alpha almost-equal-to 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.