Variable range hopping in a non-equilibrium steady state

Abstract

We propose a Monte Carlo simulation to understand electron transport in a non-equilibrium steady state (\textit{NESS}) for the lattice Coulomb Glass model, created by continuous excitation of single electrons to high energies followed by relaxation of the system. Around the Fermi level, the \textit{NESS} state approximately obeys the Fermi-Dirac statistics, with an effective temperature ($T_{eff}$) greater than the system's bath temperature ($T$). $T_{eff}$ is a function of $T$ and the rate of photon absorption by the system. Furthermore, we find that the change in conductivity is only a function of relaxation times and is almost independent of the bath temperature. Our results indicate that the conductivity of the \textit{NESS} state can still be characterized by the Efros-Shklovskii law with an effective temperature $T_{eff}>T$. Additionally, the dominance of phonon-less hopping over phonon-assisted hopping is used to explain the relevance of the hot-electron model to the conductivity of the \textit{NESS} state.