Study of Mini-Gap Regime in Au Nanowires*

The inducement of superconductivity in 70nm single crystal Au nanowires (AuNWs) via the Proximity Effect was reported in 2009 [Wang, J. et al. \textit{Phys. Rev. Lett.} \textbf{2009}, 102, 247003]. This study, carried out on 3 AuNWs of different lengths (1.0, 1.2 and 1.9 $\mu $m), showed a precipitous drop in the resistance to a fully superconducting state of the 1.0um wire; while the 1.2$\mu $m wire made the transition in 2 steps, and the 1.9$\mu $m wire never fully transitioned to a zero resistance state. This behaviour lead to the coinage of the so-called ``mini-gap'' phase in proximity induced superconducting nanowires. We are currently investigating the robustness of this ``mini-gap'' regime by parametric variations to the gold nanowire system. Looking at features such as crystallinity, AuNW diameter, electrode material, and directional magnetic field dependence, we are attempting to further illuminate the nature of this new ``mini-gap'' state.