Imaging Josephson Vortices on the Surface Superconductor Si(111)-(root7xroot3)-In using a Scanning Tunneling Microscope

TL;DR

This study uses low-temperature STM to visualize Josephson vortices on a superconducting Si(111) surface, revealing how atomic steps influence vortex behavior and the transition from Pearl to Josephson vortices.

Contribution

It provides direct imaging and analysis of Josephson vortices on a surface superconductor, elucidating the role of atomic steps and interterrace coupling in vortex dynamics.

Findings

Vortices are trapped at atomic steps after applying magnetic fields.

The transition from Pearl to Josephson vortices is observed through their elongated shapes.

Superconductivity recovers significantly within vortex cores.

Abstract

We have studied the superconducting Si(111)-(root7xroot3)-In surface using a 3He-based low-temperature scanning tunneling microscope (STM). Zero-bias conductance (ZBC) images taken over a large surface area reveal that vortices are trapped at atomic steps after magnetic fields are applied. The crossover behavior from Pearl to Josephson vortices is clearly identified from their elongated shapes along the steps and significant recovery of superconductivity within the cores. Our numerical calculations combined with experiments clarify that these characteristic features are determined by the relative strength of the interterrace Josephson coupling at the atomic step.