Critical behavior in unconventional superconductors and superfluids is established and described by the Wilson-Fisher renormalization-group method. For certain ordering symmetries a 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 superconducting and superfluid systems, in particular to itinerant ferromagnets as $\mathrm{U}{\mathrm{Ge}}_2$ and URhGe.

• Received 26 July 2006

DOI:https://doi.org/10.1103/PhysRevB.74.134514