Coexistence of competing orders with two energy gaps in real and momentum space in high-Tc superconductor Bi2Sr2-xLaxCuO6+delta

TL;DR

This study reveals the coexistence of two distinct energy gaps in high-Tc superconductor Bi2Sr2-xLaxCuO6+delta, indicating intertwined superconducting and charge order phenomena in both real and momentum space.

Contribution

It provides direct experimental evidence of two coexisting energy gaps in the superconducting phase, linking the large gap to charge order and the small gap to superconductivity.

Findings

Two distinct gaps coexist in real and momentum space.

The small gap is associated with superconductivity.

The large gap persists above Tc and relates to charge ordering.

Abstract

The superconducting phase of the high-Tc cuprates has been thought to be described by a single d-wave pairing order parameter. Recently, there has been growing evidence suggesting that another form of order, possibly inherited from the pseudogap phase above Tc, may coexist with superconductivity in the underdoped regime. Through a combined study of scanning tunneling microscopy and angle-resolved photoemission spectroscopy, we report the observation of two distinct gaps (a small-gap and a large-gap) that coexist both in real space and in the anti-nodal region of momentum space in the superconducting phase of Bi2Sr2-xLaxCuO6+delta. We show that the small-gap is associated with superconductivity. The large-gap persists to temperatures above the transition temperature Tc and is found to be linked to short-range charge ordering. Remarkably, we find a strong, short-ranged correlation between the local small- and large- gap magnitudes suggesting that the superconductivity and charge ordering are affected by similar physical processes.