Triplet superconductivity induced by screened phonon interactions in ferromagnetic compounds

We propose that screened pairing interactions mediated by phonons could give rise to a spin triplet superconductivity in ferromagnetic compounds such as ${\rm UGe_2}$. It is pointed out that the pairing interactions include anisotropic components such as those of p-, d-, f-waves in addition to dominant s-wave component due to the momentum dependence. Since the ferromagnetic long-range order coexists, there is a large splitting of the Fermi surfaces of up and down spin electrons, which suppresses singlet pairing. Therefore, triplet pairing occurs at last due to the sub-dominant anisotropic interactions, even in the absence of magnetic contribution to the pairing interactions