THE NONCONVENTIONAL LOW-BIAS ANOMALY OF THE SINGLE-ELECTRON DENSITY OF STATES IN DISORDERED INDIUM FILMS

Abstract

We have measured the single-electron density of states (DOS) of structurally-disordered superconducting indium films with the thickness ranging from 500 angstrom to 3000 angstrom. In spite of the apparent three-dimensionality of the films, the DOS shows a two-dimensional logarithmic singularity at low bias near the Fermi level, in agreement with the recent observation by others in amorphous indium/indium oxide films. The DOS also shows a crossover to a square-root anomaly at even higher bias voltages, the values of the crossover energy, however, are irrelevantly higher than the theoretical predictions.