Macroscopic Superconducting Current through a Silicon Surface Reconstruction with Indium Adatoms: Si(111)-(R7$\times$R3)-In

Abstract

Macroscopic and robust supercurrents are observed by direct electron transport measurements on a silicon surface reconstruction with In adatoms (Si(111)-(R7xR3)-In). The superconducting transition manifests itself as an emergence of the zero resistance state below 2.8 K. $I-V$ characteristics exhibit sharp and hysteretic switching between superconducting and normal states with well-defined critical and retrapping currents. The two-dimensional (2D) critical current density $J_{2D,\mathrm{c}}$ is estimated to be as high as $1.8A/m$ at 1.8 K. The temperature dependence of $J_{2D,\mathrm{c}}$ indicates that the surface atomic steps play the role of strongly coupled Josephson junctions.

4 pages, 3 figures; The error in the values of 2D critical current density $J_{2D,\mathrm{c}}$ was corrected. In the old version, the numbers were wrong by a factor of 100 due to a mechanical error. This does not affect the following analysis and conclusion