Half-Solitons in Superfluid (3)He-A: Novel pi/2-Quanta of Phase Slippage

摘要

Core structures of non-topological solitons between inequivalent vacua in superfluid 3He-A are considered. The symmetries of these A-A interfaces are analyzed, and their hard-core structures are computed in the Ginzburg-Landau regime. The authors discuss both domain walls where the orbital anisotropy l-vector is flipped (l vector -> -l vector), and those with the same l vector (x = -infinity) and l vector(x = + infinity) asymptotics. In particular, new classes of A-A boundaries are found; these novel pi/2-solutions, which can occur in the absence of a change in the asymptotic l vector field, constitute the elementary quanta of phase slippage in superfluid 3He-A. These half-solutions are ascribed to a new topological scenario for the flaring-out of vorticity in the extended (k vector, r vector) space. Edges of such walls serve to provide vortices with one quarter quantum of circulation in 3He-A.