An Intrinsic Bond-Centered Electronic Glass with Unidirectional Domains in Underdoped Cuprates

TL;DR

This study reveals unidirectional electronic domains and a bond-centered electronic glass in underdoped cuprates, linking local electronic heterogeneity to the emergence of high-temperature superconductivity.

Contribution

It introduces atomic-resolution tunneling asymmetry imaging to visualize intrinsic electronic glass and unidirectional domains in lightly hole-doped cuprates, a novel observation.

Findings

Unidirectional electronic domains are dispersed throughout cuprates.

Spatial variations in tunneling asymmetry are prominent at planar oxygen sites.

The electronic pattern suggests partial hole-localization evolving into superconductivity.

Abstract

Removing electrons from the CuO2 plane of cuprates alters the electronic correlations sufficiently to produce high-temperature superconductivity. Associated with these changes are spectral weight transfers from the high energy states of the insulator to low energies. In theory, these should be detectable as an imbalance between the tunneling rate for electron injection and extraction - a tunneling asymmetry. We introduce atomic-resolution tunneling-asymmetry imaging, finding virtually identical phenomena in two lightly hole-doped cuprates: Ca1.88Na0.12CuO2Cl2 and Bi2Sr2Dy0.2Ca0.8Cu2O8+d. Intense spatial variations in tunneling asymmetry occur primarily at the planar oxygen sites; their spatial arrangement forms a Cu-O-Cu bond centered electronic pattern without long range order but with 4a0-wide unidirectional electronic domains dispersed throughout (a0: the Cu-O-Cu distance). The emerging picture is then of a partial hole-localization within an intrinsic electronic glass evolving, at higher hole-densities, into complete delocalization and highest temperature superconductivity.