Weak localization, electron-electron interactions, and Joule heating in the presence of a microwave electric field in thin metal films.

Abstract

We have studied the electrical behavior of thin AuPd, AuFe, and Au films at low temperatures, through measurements of the resistance with special attention to the effect of a microwave electric field. Using these results in combination with the theory, we have attempted to separate the effects of weak localization, electron-electron interactions, and Joule heating. The results of this analysis yield consistent results for AuPd films with high values of the sheet resistance. However, for low-sheet-resistance films of AuPd, AuFe, and Au, the analysis suggests either that Joule heating is suppressed at microwave frequencies (as compared with that found for the same field strength at lower frequencies), or that a microwave field enhances the contribution of electron-electron interactions to the resistance. Either of these results would be at odds with current theories.