Nonreciprocal Current in Noncentrosymmetric Rashba Superconductors

We study theoretically the nonreciprocal charge transport in two-dimensional noncentrosymmetric superconductors with the Rashba spin-orbit interaction. The resistivity R depends on the current I linearly under the external magnetic field B, i.e., R=R_{0}(1+γBI), which is called the magnetochiral anisotropy. It is found that the coefficient γ is gigantically enhanced by the superconducting fluctuation with the components of both spin singlet and triplet pairings, compared with that in the normal state. This finding offers a method to quantitatively estimate the ratio of the pairing interactions between the singlet and triplet channels including its sign.