The duality of electron spin and resistivity relaxation processes in sodium and potassium metals

Abstract

Electron spin resonance (e. s. r.) spectra of small particles ( ca . 500 nm) of sodium and potassium metals have been recorded over the temperature range 4─100 K. Analysis of the e. s. r. lineshapes yields values of the electron spin-lattice relaxation rate T -1 1 . Both electron spin relaxation and electrical resistivity in the alkalis are governed by the scattering of high velocity conduction electrons by lattice phonons. The temperature dependence of T -1 1 bears a striking similarity to that of the electrical resistivity. In both cases the temperature dependence is adequately described by a Bloch-Grüneisen function for temperatures above ½ θ , where θ is the Debye temperature. If a Debye model is used to approximate the behaviour of lattice vibrational modes, the derived Debye temperatures from the spin relaxation data are about 20% lower in the particulate samples of sodium and potassium than in the corresponding bulk metals.