Anomalous Skin Effect in Metals

Abstract

AT sufficiently low temperatures and high frequencies, the mean free path of the electrons in a good conductor becomes greater than the classically predicted skin depth, and the classical skin-effect equations break down. Pippard¹ has studied the effect at liquid helium and liquid hydrogen temperatures, and Reuter and Sondheimer² have given the quantitative theory of the effect, and have interpreted Pippard's results. They found that for tin, mercury and aluminium, the experimental results implied reasonable values for the ratio σ/l of conductivity to electronic mean free path, but that for copper, silver and gold they implied values lower than the expected values by a factor of 5 or more. It was suggested that these low values were due to surface conditions differing from those in the bulk metal. In order to study this suggestion and to make a more detailed comparison with the theory than was possible on the basis of Pippard's measurements, a new investigation has been carried out in which attention has been paid to surface conditions, and the whole temperature range from 2° K. to 90° K. has been covered.