MEASUREMENTS ON THE VORTEX SHEET IN ROTATING SUPERFLUID HE-3-A

When a cylindrical container filled with superfluid He-3-A is rotated around its symmetry axis, several different configurations of quantize d vorticity are possible: which of them will be preferred depends on t he specifics how the rotating state is formed. The most unusual is the vortex sheet, a domain wall in the order parameter texture into which vortex lines are confined. This metastable structure has the lowest c ritical velocity of formation if a domain wall with the appropriate or ientation is already present in the container. In this case the vortex sheet becomes the preferred rotating state which provides the solid-b ody rotation of the superfluid component on an averaged scale. Its pre sence can be identified from the cw NMR spectrum which samples the ord er parameter texture. Here the experimental properties of the vortex s heet are reviewed, as deduced from NMR measurements.