Coexistence of triplet superconductivity and itinerant ferromagnetism

The triplet superconductivity in UGe2 and URhGe coexists with itinerant ferromagnetism such that in the pressure-temperature phase diagram the whole region occupied by the superconducting state is situated inside a more vast ferromagnetic region. In the same family metal UCoGe the pressure dependent critical lines T(curie)(P) and T(sc) (P) of the ferromagnet and the superconducting phase transitions intersect each other. The two-band multi-domain superconducting ferromagnet state arises at temperatures below both of these lines. Here I describe the symmetry and the order parameters of the paramagnet as well of the multi-domain ferromagnet superconducting states. The Josephson coupling between two adjacent ferromagnet superconducting domains is discussed. (author)