Insensitivity of the superconducting gap to variation in Tc in Zn-substituted Bi2212

TL;DR

This study investigates how the superconducting gap in Zn-substituted Bi2212 varies with Tc, revealing that Tc influences the coherence peak size but not the gap shape or magnitude, challenging existing assumptions about their relationship.

Contribution

The paper demonstrates that in Zn-substituted Bi2212, the superconducting gap remains insensitive to Tc variations, highlighting a decoupling between gap magnitude and transition temperature.

Findings

Gap shape and size are unaffected by Tc changes.

Tc controls the coherence peak size at the gap edge.

Gap is primarily governed by T*, not Tc.

Abstract

The phase diagram of the superconducting high-Tc cuprates is governed by two energy scales: T*, the temperature below which a gap is opened in the excitation spectrum, and Tc, the superconducting transition temperature. The way these two energy scales are reflected in the low-temperature energy gap is being intensively debated. Using Zn substitution and carefully controlled annealing we prepared a set of samples having the same T* but different Tc's, and measured their gap using Angle Resolved Photoemission Spectroscopy (ARPES). We show that Tc is not related to the gap shape or size, but it controls the size of the coherence peak at the gap edge.