Magnetic coupling contributions to the thermal boundary resistance between3He and metals

Abstract

In a recent experiment, Perry, DeConde, Sauls, and Stein found a thermal boundary resistance between3He and platinum that was inversely proportional to temperature and decreased with application of a magnetic field. These authors suggested an explanation of the experimental observations in terms of a hyperfine contact interaction between the helium nuclear spins in the first surface monolayer and the conduction electrons of the metal. In the present work the magnetic coupling between the electron-nuclear spin systems is investigated for the contact interaction using a realistic representation of the metallic spin susceptibility at the helium site. The longer range dipole interaction is also considered and results for copper, silver, gold, and platinum indicate that both magnetic coupling mechanisms are orders of magnitude too weak to account for experimentally observed heat transfer rates. The much larger heat transfer rate obtained by Perry et al. is traced to their overestimation of the conduction electron local density of states at the helium site. © 1987 Plenum Publishing Corporation.