Tunneling spectroscopy of Tl2Ba2CaCu2O8 single crystals and thin films

TL;DR

This study presents new tunneling spectroscopy measurements on Tl2Ba2CaCu2O8 single crystals and thin films, resolving previous discrepancies and supporting d-wave symmetry of the superconducting gap.

Contribution

It provides comprehensive tunneling data that reconcile earlier conflicting results and enhances understanding of the superconducting gap in Tl2Ba2CaCu2O8.

Findings

Measured  values range from 24-50 meV, with most above 30 meV.

Results support d-wave symmetry of the superconducting gap.

Spectra show features similar to the dip observed in Bi2Sr2CaCu2O8.

Abstract

Early electron tunneling experiments with the Tl2Ba2CaCu2O8 measured \Delta = 16-28 meV, while bulk optical experiments measured \Delta = 43-45 meV. We report new tunneling measurements of Tl2Ba2CaCu2O8 single crystals and c-axis oriented thin films, where the measured \Delta values on both sample types cover the range of 24-50 meV, with more than 70% of the junctions displaying \Delta > 30 meV. This work resolves the inconsistency between previously published results of tunneling and optical experiments. New tunneling conductances reveal improved superconducting gap region characteristics consistent with d-wave symmetry. The tunneling spectra also display features similar to the dip feature observed in Bi2Sr2CaCu2O8. We discuss our results in context of experiments reported previously on related materials.