ON THE TEMPERATURE-DEPENDENCE OF THE ELECTRONIC THERMAL-CONDUCTIVITY IN METALS WHEN THE ELECTRON AND PHONON SUBSYSTEMS ARE NOT IN LOCAL EQUILIBRIUM

The knowledge of the temperature dependence of the thermal conductivit y is necessary in many aspects. It is required, for example, as an imp ortant input parameter for the calculation of temperature distribution s in metals after interaction with laser pulses. Although extensive co mpilations exist on this subject they may be of limited value because the data were obtained under steady state conditions where the electro ns and phonons are described by a single common temperature. At short laser pulses, however, the electron and phonon subsystems are not in l ocal thermal equilibrium and have to be characterized by different tem peratures. It is shown that the validity of the often used linear depe ndence of the thermal conductivity on the electron temperature is limi ted to some few thousand kelvin and becomes definitely wrong at higher temperatures. A formula including the thermoelectric effects is deriv ed that is valid throughout the whole temperature range as well as for the case of local thermal equilibrium and nonequilibrium.