Tuning Pairing Amplitude and Spin-Triplet Texture by Curving Superconducting Nanostructures

Abstract

We investigate the nature of the superconducting 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 superconducting order parameter, with the effect that can be tailored by tuning either the RSOC strength or the carrier density. Apart from the local superconducting spin-singlet amplitude control, the geometric curvature generates non-trivial textures of the spin-triplet pairs through a spatial variation of the d-vector. By employing the representative case of an elliptically deformed quantum ring, we demonstrate that the amplitude of the d-vector strongly depends on the strength of 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 novel paths to manipulate the quantum structure of the superconducting state in RSOC nanostructures through their geometry.