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., $R=R_0(1+\gamma BI)$, which is called the magnetochiral anisotropy. It is found that the coefficient $\gamma$ 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.

Figure 1

The three field configurations which correspond to (a) ${\sigma }_{xyxx}$, (b) ${\sigma }_{xxxy}$, and (c) ${\sigma }_{xyyy}$. $B$, $E$, and $I$ in the figures represent the electric field, magnetic field, and nonreciprocal current, respectively.

Figure 2

The electric and magnetic field angle dependence of $j^{(2)}$. ${\theta }_B$ (${\theta }_E$) represents the angle between the magnetic (electric) field and the nonreciprocal current. The amplitude is normalized by ${\sigma }_{xyyy}B{E}^2$.