Abstract
We investigate pairing states realized at the (001) interface of a spin-triplet superconductor Sr2RuO4 on the basis of microscopic calculations. Because of a Rashba-type spin–orbit interaction induced at the interface, strong parity-mixing of Cooper pairs between a spin-singlet state and a spin-triplet state occurs in this system. There are also strong inter-band pair correlations between the spin–orbit split bands, in spite of the considerably large spin–orbit splitting. This is due to frustration between the spin–orbit interaction and pairing interactions. In this pairing state, time-reversal symmetry is restored, in contrast to the bulk Sr2RuO4, which is believed to be a chiral p+ip superconductor with broken time-reversal symmetry. It is demonstrated that, because of these features, the pairing state at the interface is a promising candidate for the recently proposed time-reversal invariant topological superconductor.
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