Quantitative Superfluid Helium-3 from Confinement to Bulk


Liquid helium-3 is a remarkable substance. Even prior to the discovery of superfluidity in 1972, liquid helium-3 was the paradigm of a strongly interacting Fermi liquid. At even lower temperatures, liquid helium-3 undergoes a phase transition to a p-wave Fermi superfluid. Over 40 years since its discovery, superfluid helium-3 is still the only confirmed p-wave superfluid. One of the most striking features of this superfluid is the existence of two distinct phases in the bulk liquid. These A and B phases are separated by a line of first order transitions as a function of temperature and pressure. Shortly after the discovery of p-wave superfluidity, it was realized that additional phases should be obtainable through geometric confinement. With more recent advances in materials design and fabrication, the use of confining geometries to control the superfluid helium-3 phase diagram has grown to encompass a number of ordered and disordered geometries. In this thesis I first consider the confinement problem in the Ginzburg-Landau regime, focusing on novel superfluid phases in arrays of line impurities, thin films, and nanoscale channels. In the last chapter I revisit the problem of precisely calculating bulk superfluid properties from a microscopic model. Using a quasiclassical free-energy functional approach, with newly determined quasiparticle interactions, quantitative agreement with the experimental specific heat and A-B phase boundary is achieved.

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