LOCAL HEATING IN MESOSCOPIC SYSTEMS

The thermal excitation of an impurity atom by an electron current in a mesoscopic system is investigated. Starting from the density matrix of the combined system of the electrons and the impurity, we obtain a solution to the master equation for the impurity atom in the presence of inelastic electron-impurity scattering. Explicit expressions are found for the effective temperature of the nonequilibrium electrons and for the relaxation rate of the impurity towards the thermally excited steady state. The effect of a phonon bath is included in our analysis. In the case of high bias and high lattice temperature, the impurity follows a Boltzmann distribution with a time-dependent temperature.