A mechanism of superconductivity in non-centrosymmetric system

Unconventional superconductivity in non-centrosymmetric compounds like CePt3Si, CeRhSi3, and CeIrSi3 attracts much attention. The most exotic feature of these compounds is a quite large upper critical field of superconductivity, which exceeds the Pauli limiting field. Therefore, it is considered that the possibility of spin-triplet superconductivity is not excluded in the non-centrosymmetric system. In addition, the Sigrist group has suggested that the d-vector of possible triplet superconductivity in non-centrosymmetric systems is parallel to the Rashba field, by which the inversion symmetry is broken. Based on a Hubbard model including the Rashba field, we study the superconductivity with an assumption suggested by the Sigrist group. The superconductivity is induced by spin fluctuations including anomalous spin fluctuations, which vanish in centrosymmetric systems. We will also discuss property of the superconducting state.