Texture and Vortex of Rotating Superfluid 3He-A in Parallel-plate Geometry

Unique types of textures and vortices of superfluid 3He in restricted geometries have been discussed. We investigated cw-NMR in rotating 3He A-phase in parallel plate geometries with gaps of 12.5 μm at 3.05 MPa. We observed a very sharp spectrum at rest which had shifted negatively as f=fL−0.93fA(T), where fA(T) is the full transverse dipole shift in A-phase. The large negative shift of 0.93fA(T) indicates that l⊥d. When we rotated the sample with rotation speed Ω faster than the critical ΩFr, a new satellite signal appeared nearly at fL. The satellite signal intensity increased with increasing Ω, reached a maximum at Ωc and slowly decreased up to the maximum Ω of 2π rad/s. When Ω decreased from the maximum speed, the satellite signal rapidly decreased and disappeared at 5.5 rad/s down to zero rad/s. We measured the temperature dependence of the satellite signal intensity, ΩFr and Ωc. We propose a model for the satellite signal, which is attributed to spin wave in Fréedericksz transition region induced by the counter flow. We also compare the satellite signal with Kee and Maki’s bound pair of HQV.