Effects of disorder in parity violating superconductors

In materials without an inversion center of symmetry the spin degeneracy of the conducting band is lifted by spin orbit coupling (SOC). If the splitting of the non-degenerate quasi-particle energy spectrum is larger than the energy scale of the superconducting gap, i.e., $\alpha > k_{B}T_{c}$, only one spin-triplet pairing channel survives to the lack of the inversion symmetry. In the limit of larger $\alpha$, i.e, $\alpha >> k_{B}T_{c}$, the spin susceptibility in case of spin-singlet and protected spin-triplet paring are similar, making it difficult to determine the pairing type through Knight shift measurements. However, Anderson's theorem concerning non-magnetic impurities still holds. This should make possible to discriminate experimentally at least between conventional and unconventional pairing. If the density of states at the Fermi level is different for the two non-degenerate bands, the spin-triplet and the spin-singlet pairing channels mix, modifying further the response of the system on disorder. The impurity dependence of the critical temperature, the spin susceptibility, and the paramagnetic limiting field have been studied using the Born approximation for various combinations of the pairing channels, and different distributions of the conduction electrons on the two non-degenerate bands.