The Duality of Electron Spin and Resistivity Relaxation Processes in Sodium and Potassium Metals

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-11. 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-11 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 ½θ, 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.