Solidification of the third helium layer on graphite

Abstract

We report heat capacity and magnetization measurements of 3He adsorbed on graphite pre-plated by a solid bilayer of 4He. The first 3He layer adsorbed on this composite substrate remains fluid up to and beyond layer promotion. However it is observed to solidify significantly before the second 3He layer is completed. Remarkably, at fluid coverages on the verge of solidification, we observe a distinctive heat capacity and magnetisation maximum, which occurs at progressively lower temperatures as the coverage is increased. Possible magnetic instabilities in the fluid and analogues with heavy fermion systems are discussed.