LXXIII. Scattering of phonons and electrons by imperfections in a metal

Abstract

Heat transport in superconducting metals is a complex phenomenon, and many details still await a quantitative explanation. K _n, the thermal conductivity in the normal state (restored by a weak magnetic field), is due almost entirely to conduction electrons, unless the metal is very impure. K _s, the thermal conductivity in the superconducting state, is more complicated; however, recent experiments (Mendelssohn and Renton 1953, 1955, Laredo 1955) suggest that at low temperatures K _s is mainly due to phonons. In comparison with the normal metal the effect of the latter is much enhanced. This is because in a superconductor with falling temperature, the electrons are rapidly losing their entropy and can neither conduct heat nor scatter phonons.