THE MAGNETIC ENVELOPE OF THE PROPAGATING A-B BOUNDARY IN HE-3

We present a theory of the magnetic properties of the A-B phase bounda ry propagating in He-3 under conditions of low temperature and therefo re with slow magnetic relaxation. Owing to the difference in susceptib ility between the phases, a nonequilibrium magnetization appears behin d the moving boundary. This magnetization is transported in the form o f step solitons into the bulk A and B phases by a new spin supercurren t mode, related to the longitudinal NMR, which explains the experiment ally observed magnetic precursor travelling ahead of the boundary.