Ordered Phases of Solid and Liquid Helium Three

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Quantum fluids and solids have served as important topics of research in their own right, and as model systems for understanding similar physical phenomena exhibited in more complex materials. They propose here three series of experiments intended to further their physical understanding in both these regards. The first series will involve ultrasound studies of the U2D2 phase of solid 3He with the intention of searching for the lattice distortion expected to occur upon nuclear spin ordering, and to more fully measure the magnetic Gruneisen tensor. These studies shoud help answer a number of remaining fundamental questions regarding this model magnetic system. The second series will involve a search for superfluidity in two dimensional sub-monolayer films of 3He adsorbed on top of 2-4 monolayer films of superfluid 4He. If successful, this search will provide us with an entirely new BCS superfluid state, which should shed light on possible 2D superconducting states. Finally, they will investigate the process by which the B-phase of superfluid 3He is nucleated from the A- phase superfluid. This seemingly simple problem is a particularly tempting one because we know so much about these phases that they feel they should be able to fully understand this transition. Further, the relevant length scale of the A to B nucleation is so long that this transition represents a rare opportunity to understand in equisite detail inhomogeneous nucleation at a first order phase transition.