Nonequilibrium Zero-Bias Anomaly in Disordered Metals

We extend the theory of a zero-bias anomaly (ZBA) in the tunneling density of states of a diffusive metallic film to out-of-equilibrium conditions. An effective action describing virtual fluctuations out of equilibrium is derived. The singular behavior of the equilibrium ZBA is smoothed out by real processes of inelastic scattering.

Figure 1

TDOS vs energy for the double-step distribution function (17) with $a=0.5$. Left column: from top to bottom $g=100$, 10. Right column: $g=1$.