Spin Dynamics and Strong Coupling in Helium Three

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9314025 Halperin Technical Abstract: The project employs nuclear magnetic resonance to investigate the superfluid phases of 3He. The research involves high precision measurements of the magnetic moment of the helium in the A and B phases, as well as determination of the contribution of the dipole-dipole coupling energies to the superfluid free energy. The novel dilute mixtures of 4He in 4He, found only in constrained geometries of aerogels will also be investigated to characterize the miscibility gap in these systems and to investigate diffusion and relaxation phenomena in these new materials. The NMR studies of molecular organic solids will focus on fundamental questions concerning the origin of the metallic state in these quasi-one- dimensional solids. The experiments will involve ultralow temperatures and high magnetic fields. Non-technical abstract: The research project employs low temperature nuclear magnetic resonance to study the behavior of superfluid phases of 3He. These systems display unusual quantum effects at very low temperatures. The information obtained in these superfluid systems is of fundamental interest, and also is of interest in connection with other Fermi liquid systems, such as the high temperature superconductors. Another part of the project involves studies of thin films of dilute 4He in 3He constrained in the diaphanous, ultrahigh surface area aerogel materials. The research will provide information about surface interactions in these materials, as well as providing fundamental information about phase behavior such as miscibility of the two isotopes of helium. Finally, the project includes NMR studies of high purity molecular organic solids which display metallic character with the conductivity having a quasi-one-dimensional anisotropy. Here the focus is on fundamental aspects of the phase transition from an insulating to conducting state. ***