Tuning pairing amplitude and spin-triplet texture by curving superconducting nanostructures

Abstract

We investigate the nature of the superconducting (SC) state in curved nanostructures with Rashba spin-orbit coupling (RSOC). In bent nanostructures with inhomogeneous curvature we find a local enhancement or suppression of the SC order parameter, with the effect that can be tailored by tuning either the RSOC strength or the carrier density. Apart from the local SC spin-singlet amplitude control, the geometric curvature generates nontrivial textures of the spin-triplet pairs through a spatial variation of the d⃗ vector. By employing the representative case of an elliptical quantum ring, we demonstrate that the d⃗ vector strongly depends on the local curvature and it generally exhibits a three-dimensional profile whose winding is tied to that of the single electron spin in the normal state. Our findings unveil paths to manipulate the quantum structure of the SC state in RSOC nanostructures through their geometry.

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