Experimental and theoretical study of the electron-phonon scattering rate in potassium

Limiting-point radio-frequency size effect measurements have been performed in potassium to measure the anisotropy and magnitude of the electron-phonon scattering rate. The anisotropy is too small to be resolved by the method, and is estimated to be less than 10 per cent at low temperatures. Theoretical calculations confirm the small anisotropy, but yield a rate at least 40 per cent larger than that observed.