Low Temperature Magnetization of Two Dimensional 3He on Three Layers of HD Preplated Graphite

We have measured the low temperature magnetization of submonolayer 3He on three layers of HD preplated graphite. NMR measurement has been performed by progressively adding 4He to the system, to prevent 3He atoms from being trapped in substrate heterogeneities and to change the areal density of 3He. The exchange constant (J) is found to have a similar density dependence to that for two layers of HD preplated one. The magnetization in the antiferromagnetic region increases gradually down to 100 (mu)K and shows no evidence corresponding to a spin gap.