Temperature dependence of the two-dimensional electronic density of states in disordered metal films

We present measurements of the temperature dependence of the conductance of a tunnel junction of the form Al/oxide/disordered-granular-Ag-film at low temperatures. From these measurements we deduce that the logarithmic corrections to the two-dimensional density of states due to disorder-enhanced Coulomb interactions depend on temperature. Specifically, for sheet resistances 1.35 k{Ω}/{}R_6.12 k{Ω}/{} and temperatures 0.07 KT6.0 K the logarithmic singularity in the density of states centered on the Fermi energy is sharp at low temperatures and smears out as the temperature increases. Our data are consistent with a model which attributes the temperature dependence of the density of states to a redistribution of the zero-temperature energies of the quasiparticle states over an energy range of the order of kBT.