Two dimensional "3He adsorbed on Grafoil plated with a bilayer of HD

"3He films adsorbed on graphite preplated with a bilayer of hydrogen deuteride were studied by heat capacity measurements, in a nuclear demagnetisation cryostat down to temperatures below 1mK. The work focused on several areas of interest in 2D "3He. Firstly coverages approaching solidification were investigated. Here we observed an apparent divergence in the effective mass of the "3He quasi-particle as it approached solidification at a density in agreement with that predicted by the #sq root#7x#sq root#7 commensurate phase. We interpret this in terms of a Mott-Hubbard transition between a 2D Fermi liquid and a magnetically disordered solid occurring via the Brinkman-Rice scenario. We also observe finite temperature corrections to the linear heat capacity of the formT"2 going over to TlnT. Further investigations were carried out into solid coverages in which "3He forms a two-dimensional quantum solid of spin 1/2 particles whose magnetism is influenced by reduced dimensionality, exchange and geometrical frustration. Here we extract the exchange parameter J_c and combine it with complementary values of J_#chi#, obtained in previous magnetisation measurements. We observe larger values of J than seen in the second layer of "3He on bare graphite. Promotion to a fluid overlayer occurs at 6.8nm"-"2 soon after which there is a crossover from antiferromagnetic to ferromagnetic exchange. The design and construction of an experimental cell for carrying out low field DC SQUID pulsed NMR measurements on "3He adsorbed on Grafoil is discussed. This cell was mounted in the ULT facility described in chapter 4. The thesis contains the preliminary results obtained by performing pulsed NMR at 50kHz on 1.3 layers of "3He adsorbed on Grafoil between 0.5 and 250 mK. The signal size detected was consistent with the prediction based on the specifications of the coil set and surface area of the cell. The cell was mounted in our new ULT Facility, the installation of which is described in this thesis. (author)SIGLEAvailable from British Library Document Supply Centre- DSC:DXN053326 / BLDSC - British Library Document Supply CentreGBUnited Kingdo