Scanning tunneling microscopic evidence of interface enhanced high-Tc superconductivity in Pb islands grown on SrTiO3

TL;DR

This study provides scanning tunneling spectroscopy evidence that Pb islands grown on SrTiO3 exhibit interface-enhanced superconductivity with significantly higher transition temperatures and energy gaps than bulk Pb, suggesting a potential new high-Tc superconductor.

Contribution

It demonstrates that Pb thin film islands on SrTiO3 show interface-enhanced high-Tc superconductivity with larger energy gaps and transition temperatures, revealing a new pathway for high-Tc superconductor development.

Findings

Superconducting gap up to 10 meV in Pb islands

Transition temperature estimated at 47 K, seven times higher than bulk Pb

Superconductivity depends on island thickness and volume

Abstract

The discovery of the interface enhanced superconductivity in the single layer film of FeSe epitaxially grown on SrTiO3 substrates has triggered a flurry of activity in the field of superconductivity. It raised the hope to find more conventional high-Tc superconductors which are purely driven by the electron-phonon interaction at ambient pressure. Here we report the experimental evidence from the measurement of scanning tunneling spectroscopy for the interface enhanced high-Tc superconductivity in the Pb thin film islands grown on SrTiO3 substrates. The superconducting energy gap of the Pb film is found to depend on both the thickness and the volume of the islands. The largest superconducting energy gap is found to be about 10 meV, which is 7 times larger than that in the bulk Pb. The corresponding superconducting transition temperature, estimated by fitting the temperature dependence of the gap values using the BCS formula, is found to be 47 K, again 7 times higher than that of the bulk Pb.