THE PROPERTIES OF THIN ^{3}He-^{4}He SUPERFLUID FILMS

Abstract

Thin3 He-4 He physisorbed films are examples of strongly interacting, quasi two-dimensional, fermion-boson mixture systems. The properties of the mixture systems can be tuned by changing the substrate or the 4 He film thickness. In this paper, we discuss the ground-state and magnetic groundstate of the 3 He subsystem and also the interactions between the excitations of the 4 He superfluid film with the single-particle excitations of the adsorbed 3 He. The ground-state of the 3 He system is calculated using a model for the 3 He-3 He effective interaction in the static 4 He film which explicitly includes the effective interaction due to exchange of virtual film excitations (ripplons). This latter effective interaction is evaluated in the random phase approximation and is shown not to be capable of causing the 3 He system to be self-bound. We discuss the evidence from magnetization, third sound and heat capacity measurements that the 3 He first transverse excited state is being occupied prior to monolayer completion.