Energy gap evolution in the tunneling spectra of Bi2Sr2CaCu2O8+d

TL;DR

This study investigates the evolution of energy gaps in Bi2Sr2CaCu2O8+d, revealing two distinct pseudogaps with different energy scales and their relation to superconductivity.

Contribution

It identifies and characterizes two types of pseudogaps in Bi2212, detailing their energy scales and temperature dependence, which advances understanding of the pseudogap phenomenon.

Findings

Two pseudogaps with different energy scales identified

The smaller pseudogap develops below T* and correlates with the superconducting gap

The smaller pseudogap evolves smoothly into the superconducting gap without closing at Tc

Abstract

On the basis of the tunneling spectra of Bi2212, we report that there exist two kinds of pseudogaps; one with a characteristic energy comparable to the superconducting (SC) gap and another one that is 3 to 4 times larger. The smaller energy-scale pseudogap (SPG) develops progressively below temperature T*, which nearly scales with the SC gap amplitude D0, in addition to the larger energy-scale pseudogap (LPG). The SPG smoothly develops into the SC-state gap with no tendency to close at Tc.