Theory of the Spin Relaxation of Conduction Electrons in Solid and Liquid Metals

A formula for the spin-relaxation time (SRT) of conduction electrons in solid metals, obtained previously from a heuristic extension to solids of a theory proposed for liquid metals, is rigorously derived here. In this theory, which is equivalent to Yafet's within the one-phonon approximation, the SRT is expressed in terms of the dynamical-structure factor of the metal which includes the actual spectrum of lattice excitations and automatically takes into account the umklapp processes exactly. The SRT of solid sodium and potassium are calculated as a function of temperature using a simple model for the structure factor. The results are compared with available experimental data and the agreement is found to be good down to about 40 ^∘{}K. Comments on the origin of the discrepancy below this temperature are made. The enhancement effect of the electron-electron interaction on the SRT is discussed.