Predominantly Superconducting Origin of Large Energy Gaps in Underdoped Bi2Sr2CaCu2O8-d from Tunneling Spectroscopy

TL;DR

This study presents tunneling spectroscopy data on underdoped Bi2Sr2CaCu2O8-d, revealing large energy gaps that are primarily of superconducting origin, significantly larger than in overdoped samples, with implications for understanding high-temperature superconductivity.

Contribution

The paper provides new tunneling measurements showing that large energy gaps in underdoped Bi2Sr2CaCu2O8-d are mainly due to superconductivity, clarifying the nature of the pseudogap.

Findings

Energy gaps of 51-57 meV observed in underdoped crystals.

Gaps are nearly three times larger than in overdoped samples.

Spectral analysis indicates these gaps are predominantly superconducting.

Abstract

New tunneling data are reported in underdoped Bi2Sr2CaCu2O8-d using superconductor-insulator-superconductor break junctions. Energy gaps, Delta, of 51+2, 54+2 and 57+3 meV are observed for three crystals with Tc=77, 74, and 70 K respectively. These energy gaps are nearly three times larger than for overdoped crystals with similar Tc. Detailed examination of tunneling spectra over a wide doping range from underdoped to overdoped, including the Josephson IcRn product, indicate that these energy gaps are predominantly of superconducting origin.