Evolution of Charge and Pair Density Modulations in Overdoped Bi2Sr2CuO6+delta

TL;DR

This study uses scanning tunneling microscopy to track how charge order and pair density modulations evolve in overdoped Bi2Sr2CuO6+δ, revealing the disappearance of charge puddles and nematicity as superconductivity diminishes.

Contribution

It provides new insights into the evolution of charge order and nematicity across doping levels in cuprates, linking these to superconductivity suppression.

Findings

Charge order transitions from long-range checkerboard to short-range puddles.

Charge puddles exhibit unidirectional nematic structure and pair density modulations.

Nematicity and charge puddles vanish in the non-superconducting overdoped regime.

Abstract

One of the central issues concerning the mechanism of high temperature superconductivity in cuprates is the nature of the ubiquitous charge order and its implications to superconductivity. Here we use scanning tunneling microscopy to investigate the evolution of charge order from the optimally doped to strongly overdoped Bi2Sr2CuO6+{\delta} cuprates. We find that with increasing hole concentration, the long-range checkerboard order gradually evolves into short-range glassy patterns consisting of diluted charge puddles. Each charge puddle has a unidirectional nematic internal structure, and exhibits clear pair density modulations as revealed by the spatial variations of superconducting coherence peak and gap depth. Both the charge puddles and the nematicity vanish completely in the strongly overdoped non-superconducting regime, when another type of short-range order with root2 * root2 periodicity emerges. These results shed important new lights on the intricate interplay between the intertwined orders and the superconducting phase of cuprates.