Ferromagnetic Superconductors

The coexistence of itinerant electron ferromagnetism and superconductivity in UGe 2 and ZrZn 2 raises the question if itinerant ferromagnetism is a universal precondition for certain forms of superconductivity. The d.c. magnetization of both compounds provides evidence of nearly critical, longitudinal spin fluctuations in the ferromagnetically ordered regime where superconductivity is observed. When taken together with key characteristics of the superconductivity, this is consistent with magnetically mediated pairing in these materials.