ESR evidence for phonon-mediated resistivity in alkali-metal-doped fullerides

Abstract

The temperature dependence of ESR linewidths and $g$ values for the fulleride superconductors ${\mathrm{K}}_{3}$${\mathrm{C}}_{60}$, ${\mathrm{Rb}}_{3}$${\mathrm{C}}_{60}$, and ${\mathrm{Na}}_{2}$Cs${\mathrm{C}}_{60}$ are reported. Following the Elliott-Yafet theory of electronic relaxation in metals, we compare the temperature dependence of the linewidth divided by the square of the difference of $g$ from the free-electron value with the temperature dependence of the resistivity. We show that the Elliott relation applies for all three compounds, implying a normal-state resistivity dominated by electron-phonon interactions.