Asymmetric Little-Parks Oscillations in Full Shell Double Nanowires

TL;DR

This paper demonstrates that slight misalignments in magnetic field orientation can induce asymmetric Little-Parks oscillations in double nanowire shells, revealing new effects relevant for topological superconductivity.

Contribution

It shows that small field misalignments cause asymmetric oscillations in double nanowire shells, a novel observation in superconducting flux phenomena.

Findings

Asymmetry in Little-Parks oscillations due to field misalignment

Oscillations observed in both destructive and non-destructive regimes

Field orientation critically affects superconducting behavior

Abstract

Little-Parks oscillations of a hollow superconducting cylinder are of interest for flux-driven topological superconductivity in single Rashba nanowires. The oscillations are typically symmetric in the orientation of the applied magnetic flux. Using double InAs nanowires coated by an epitaxial superconducting Al shell which, despite the non-centro-symmetric geometry, behaves effectively as one hollow cylinder, we demonstrate that a small misalignment of the applied parallel field with respect to the axis of the nanowires can produce field-asymmetric Little-Parks oscillations. These are revealed by the simultaneous application of a magnetic field perpendicular to the misaligned parallel field direction. The asymmetry occurs in both the destructive regime, in which superconductivity is destroyed for half-integer quanta of flux through the shell, and in the non-destructive regime, where superconductivity is depressed but not fully destroyed at these flux values.