First-principles determination of the ultrahigh electrical and thermal conductivity in free-electron metals via pressure tuning the electron-phonon coupling factor

Abstract

Responses of materials at high pressures can reveal fundamental insights into properties of condensed matter that are otherwise masked under ambient conditions. Using first-principles calculations to determine the electron-phonon interactions of free-electron metals at high pressures, we show that the electrical and thermal transport properties of aluminum, gold, and silver can be significantly enhanced with the application of high pressures. This is partly attributed to the decrease in electron-phonon coupling with increasing pressures. At elevated temperatures, under these high-pressure conditions, the thermal conductivity of aluminum is amongst the highest of any known material, surpassing the thermal conductivity of diamond at ambient pressure. Moreover, through calculation of the spectrally resolved electron-phonon coupling parameter at high pressures, we show an increased contribution to electron-phonon coupling from high-frequency longitudinal phonon modes scattering with electrons in aluminum. Using the same analysis with gold and silver, we show that low frequency acoustic phonon scattering with electrons is increased at high pressures. This work provides valuable insights into the electron-phonon scattering processes occurring under high pressures, which gives rise to new regimes of electrical and thermal transport properties in metals.