Magnetically stabilized AB interface in rotating superfluid 3He

How do vortex lines in the A and B phases of superfluid 3He interact at theAB phase boundary, when they have different structure and quantization in these two phases? We discuss an experimental setup where theAB interface is stabilized in a long cylindrical sample with a magnetic barrier field. It divides the sample in A- and B-phase sections which are maintained in homogeneous low-field NMR environments over the temperature interval where the supercooled A phase exists. With two independent NMR spectrometers the vortex lines in the two phases can be studied as a function of the rotation velocity of the cryostat. Simultaneously, by adjusting the barrier field and temperature, the sample can be changed from single phase to two-phase configurations, or to one with two AB interfaces. Using this setup the first example of a shear-flow instability in superfluids was discovered (Phys. Rev. Lett. 89 (2002) 155301).