Superfluid 3He in very confined regular geometries

Superfluid 3He in very narrow slab and cylindrical geometries is studied using the Ginzburg-Landau approach. It is found that, in the case of very narrow slabs, the effect of the boundary is to favor the formation of the A phase. At lower temperatures, this A phase is unstable against a deformed B phase. Both states are locally stable and can be supercooled or superheated. The phase diagram for 3He in a narrow slab resembles that of 3He in a magnetic field. The superfluid densities along the channel for both diffusive and specular boundary conditions are computed. Similar results are obtained for a cylindrical geometry. In addition, we present an analytic scheme for determining the order parameter in other geometries in the ''very strongly confined'' limit