Structure of the Surface Vortex Sheet between Two Rotating 3He Superfluids

We study a two-phase sample of superfluid ³He where vorticity exists in one phase (³He-A) but cannot penetrate across the interfacial boundary to a second coherent phase (³He-B). We calculate the bending of the vorticity into a surface vortex sheet on the interface and solve the internal structure of this new type of vortex sheet. The compression of the vorticity from three to two dimensions enforces a structure which is made up of 1/2-quantum units, independently of the structure of the source vorticity in the bulk. These results are consistent with our NMR measurements.