Theory of the surface tension maximum of liquid 3He

Recently Matsumoto et al. performed very precise measurements of the surface tension of liquid He-3, sigma (T), at low temperatures and found that sigma (T) exhibits a small maximum at about 100 mK. Existing theories are unable to explain this anomaly. On the basis of a local approximation for the entropy in which the Fermi liquid effect is included, we can evaluate the variation of sigma (T), Delta sigma (T) = sigma (T) -sigma (0), as a function of T and of the number density (or the interaction strength). It is found that dc(T) consists of tyro terms; a T-2 terra and T-4 In T term. We predict that, for the density of real liquid He-3, Delta sigma exhibits a tiny minimum and a small but relatively larger maximum. This prediction explains qualitatively and quantitatively all salient features of the observed Delta sigma (T).