Superconductivity and quantum oscillations in crystalline Bi nanowires

TL;DR

This paper reports the discovery of superconductivity in crystalline bismuth nanowires below 1.3 K, with quantum oscillations indicating coexistence of superconducting and normal metallic states at the surface.

Contribution

It provides experimental evidence of superconductivity and quantum oscillations in Bi nanowires, highlighting the role of surface interfaces in these phenomena.

Findings

Superconductivity observed below 1.3 K in 72 nm Bi nanowires.

Periodic resistance oscillations with magnetic flux quantum in a parallel field.

Shubnikov-de Haas oscillations indicating normal metallic behavior in the surface shell.

Abstract

While bulk bismuth (Bi) is a semimetal, we have found clear evidence of superconductivity in a crystalline 72 nm diameter Bi nanowire below 1.3 K. In a parallel magnetic field (H), the residual resistance of the nanowire below Tc displays periodic oscillations with H, and the period corresponds to the superconducting flux quantum. This result provides evidence that the superconductivity comes from the interface shell between Bi and the surface oxide. In a perpendicular H, the resistance in the superconducting state shows Shubnikov-de Haas (SdH) oscillations, a signature of a normal metal. These results indicate a novel coexistence of Bosonic and Fermionic states in the surface shell of nanowires.