Nuclear magnetic resonance investigations of two-dimensional ³He

Abstract

The magnetization of 3 He adsorbed on Grafoil measured at 3 mK displays a ferromagnetic peak as a function of coverage (around 2.5 layers) substantially above free spin value. This behavior is interpreted as the result of a large ferromagnetic exchange interaction between solid in the second layer and the liquid. Solid–liquid coexistence and subsequent compression of the solid in the second layer determine the peak shape. In-plane exchange is shown to be small by measurements at low densities in the first layer. The solid–liquid exchange mechanism explains the ferromagnetic effects observed in bulk liquid 3 He confined in Grafoil; it should exist, with the same magnitude, at the solid–liquid interface of bulk 3 He.