Low-temperature magnetothermopower of silver

Abstract

A slug technique has been used to measure the thermoelectric power of silver at cryogenic temperatures, and its dependence on temperature and longitudinal magnetic field. Seven high-purity samples of various crystallographic orientations have been investigated in fields up to 5 T from 2 to 7 K, and the results constitute a broad survey of the field. Behaviour similar in form to the longitudinal magnetoresistance has been generally observed, and a tentative analysis for the zero-field and high-field limits has been attempted. The marked anisotropy can be assigned to both the diffusion and phonon drag components of the thermo-power, and in the latter case a computation based on an analytical model of the Fermi surface gives semi-quantitative agreement. It also reveals the dominant role played by the neck regions in determining the sign and magnitude of the phonon drag component and its high field limiting value.