Nuclear magnetic resonance investigations of two-dimensional 3He

Abstract

The magnetization of 3He 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 3He confined in Grafoil; it should exist, with the same magnitude, at the solid–liquid interface of bulk 3He.