Suppressed antinodal coherence with a single d-wave superconducting gap leads to two energy scales in underdoped cuprates

TL;DR

This study reveals that the two energy scales observed in underdoped cuprates are due to suppressed antinodal coherence within a single d-wave superconducting gap, challenging the notion of two distinct gaps.

Contribution

The paper demonstrates that two energy scales in underdoped cuprates can be explained by a single d-wave gap with reduced antinodal coherence, without requiring two separate gaps.

Findings

Two energy scales are linked to coherent excitations disappearing at Tc.

A single d-wave gap with suppressed antinodal spectral weight explains experimental data.

The model unifies spectroscopic and transport measurements.

Abstract

Conventional superconductors are characterized by a single energy scale, the superconducting gap, which is proportional to the critical temperature Tc . In hole-doped high-Tc copper oxide superconductors, previous experiments have established the existence of two distinct energy scales for doping levels below the optimal one. The origin and significance of these two scales are largely unexplained, although they have often been viewed as evidence for two gaps, possibly of distinct physical origins. By measuring the temperature dependence of the electronic Raman response of Bi2Sr2CaCu2O8+d (Bi-2212) and HgBa2CuO4+d (Hg-1201) crystals with different doping levels, we establish that these two scales are associated with coherent excitations of the superconducting state which disappears at Tc. Using a simple model, we show that these two scales do not require the existence of two gaps. Rather, a single d-wave superconducting gap with a loss of Bogoliubov quasiparticle spectral weight in the antinodal region is shown to reconcile spectroscopic and transport measurements.