Existence of superconducting domain walls in ferromagnets

A BCS model incorporating the orbital effect of the magnetic induction and the paramagnetic effect of the exchange field is used to investigate the conditions for the formation of an infinitesimal superconducting nucleus localized at domain walls in ferromagnets. It is shown that a solution of this type always exists in reentrant ferromagnetic superconductors, at least in the metastability region of the FN (ferromagnetic normal) phase. The existence of superconducting domain walls in the stable FN phase of ideal ferromagnets remains an open question, since the transition to this state is apparently of first order and the transition parameters are unknown. From the standpoint of realizing superconducting domain walls it seems more promising to consider reentrant superconductors possessing an irregular magnetic subsystem without a coexistence phase and having a small exchange contribution to the magnetic energy, i.e., compounds such as Ho/sub 1-x/Y/sub x/Mo6S8