Theory of proximity effect in two-dimensional unconventional superconductor with Rashba spin-orbit interaction

We study the anomalous proximity effect in diffusive normal metal (DN)/unconventional superconductor junctions, where the local density of states (LDOS) in the DN has a zero-energy peak due to the penetration of the odd-frequency spin-triplet s-wave pairing. In this study, we consider a two-dimensional unconventional superconductor on the substrate in the presence of a Rashba spin-orbit coupling (RSOC) $\lambda$, where the Rashba vector is parallel with the $z$-direction. The anomalous proximity effect, originally predicted in spin-triplet p-wave superconductor junctions, is sensitive to the RSOC when the direction of the $\mathbf{d}$-vector is parallel with the $z$-direction. It disappears with the increase of $\lambda$. When the direction of the $\mathbf{d}$-vector is on the $xy$-plane, the zero-energy surface Andreev bound states (ZESABS) can remain with the increase of $\lambda$ and an anomalous proximity effect exists even for large $\lambda$ values. On the other hand, the anomalous proximity effect can be switched on by the large $\lambda$ values in the spin-singlet d_{xy}-wave superconductor junctions. The resulting zero-energy LDOS and the magnitude of the odd-frequency spin-triplet s-wave pair amplitude increase with the increase of $\lambda$.