Superfluid helium-3 in cylindrical restricted geometries : a study with low-frequency NMR

Abstract

This thesis concerns the symmetry, phase, and order parameter of the superfluid helium-3 in restricted geometries in combination with a magnetic field. Two cylindrical containers are constructed for which the axis is aligned with the magnetic field. The first cell has a diameter (540 nm) of only a few times the size of the Cooper pairs, designed to find a new superfluid phase, namely the polar has. The second container has a diameter of 1 mm, which is the ideal size to create a potential (in the B-phase) for spin waves. To probe any superfluid phase, or spin waves, we use Nuclear Magnetic Resonance (NMR) Techniques. As the superfluids have an anisotropic susceptibility, it is an excellent tool to distinguish the different phases. However, as our samples are relatively small in volume, and the experiments needs to be performed in low magnetic field to prevent additional symmetry breaking, a very sensitive read-out magnetic resonance detection system needs to be developed, which is accomplish by creating an LC-circuit which maintains an ultra-high quality factor as it is combined with a weakly coupled transformer.