Magnetic effects on the phase transitions in unconventional superconductors

A new critical behavior in unconventional superconductors and superfluids is established and described by the Wilson-Fisher renormalization-group method. For certain symmetries of order a new type of fluctuation-driven first order phase transitions at finite and zero temperature are predicted. The results can be applied to a wide class of ferromagnetic superconductive and superfluid systems, in particular, to itinerant ferromagnets as UGe_2 and URhGe.