Density of states of amorphous GdxSi1-x at the metal-insulator transition

We have determined the electronic density of states of amorphous GdxSi1-x, N-GdSi(E), in the vicinity of the metal-insulator transition by measuring t he tunneling conductance dI/dV across a GdxSi1-x/oxide/Pb tunnel junction a t low T (T approximate to 100 mK). By applying a magnetic field we can tune through the metal-insulator transition and simultaneously measure the tran sport and N(E) on a single sample. We find a smooth transition from a metal with strung Coulomb interactions to a developing Coulomb gap in the insula ting regime. In the metallic region N-GdSi(O) scales approximately with sig ma(2).