Spin wave and vortex excitations of superfluid 3He-A in parallel-plate geometry

Quantized vortices with half-integer circulation, which are forbidden from existing in a conventional superfluid because of the single valueness of the wave function, are theoretically predicted to exist in superfluid He-3-A if the order parameters (l) over cap and (d) over cap form (l) over cap perpendicular to(d) over cap texture. To form the (l) over cap perpendicular to(d) over cap texture, we confined the superfluid between parallel plates with a 12.5 mu m gap and applied a magnetic field of H=26.7 mT perpendicular to the plates to take NMR and orient (d) over cap perpendicular to (l) over cap. NMR spectra exhibit a negative-shift peak which probes that the uniform (l) over cap perpendicular to(d) over cap texture is realized in our cell and show a new satellite signal under rotation. The rotation dependence of the satellite signal is interpreted that a Freedericksz transition of (l) over cap texture is induced by rotation above 1.0 rad/s and vortices start to appear above 1.8 rad/s.