Superfluid 3He in rotation
Experiments on vortices in rotating superfluid 3He have revealed phenomena which have not been observed in any other quantum liquid and have implications in fields beyond low-temperature physics. In 3He-A, vorticity may be supported by a continuous winding of the order parameter which gives rise to the observed continuous coreless vortices with two flow quanta. Exotic vortices with half-integer circulation quanta may also exist in this phase. In 3He-B, an abrupt change in the vortex-core structure has been explained theoretically as a topological phase transition involving half-quantum vortices. NMR experiments on rotating 3He-B have revealed that the cores of vortices observed possess spontaneously broken parity, manifested by their ferromagnetic superfluid cores.
Magnetic Vortices in Rotating Superfluid 3He-B
Rotating superfluid /sup 3/He-B is found to possess a new contribution to the NMR frequency shift, which changes sign on reversal of either the angular velocity of rotation or the magnetic field. For p = 29.3 bars this gyromagnetic effect shows a discontinuity in magnitude at the first-order phase-transition temperature T/T/sub c/ = 0.6, at which a change in the vortex core structure takes place. These observations support the conclusion that the vortex core possesses a spontaneous intrinsic magnetization.
Hydrodynamic shifts in the NMR of superfluid 3He
A Ginzburg-Landau expansion is used to derive the effect of uniform hydrodynamic flow on the equilibrium configuration of B-3He and A-3He. Leggett's theory determines the corresponding dynamic magnetic phenomena. Increasing flow velocity shifts both the cw resonance frequencies and the ringing signal after a sudden increment in the static magnetic field.