Anomalously Strong Near-Neighbor Attraction in Doped 1D Cuprate Chains

TL;DR

This study investigates doped one-dimensional cuprate chains, revealing a strong near-neighbor attraction that influences their electronic properties and may be relevant for understanding high-temperature superconductivity.

Contribution

It introduces the discovery of a significant near-neighbor attraction in doped 1D cuprates, supported by spectroscopic data, which extends beyond simple Hubbard model predictions.

Findings

Identification of doping evolution of holon and spinon branches

Observation of a folding branch inconsistent with simple Hubbard model

Quantitative explanation of experiments by strong near-neighbor attraction

Abstract

In the cuprates, one-dimensional chain compounds provide a unique opportunity to understand the microscopic physics due to the availability of reliable theories. However, progress has been limited by the inability to controllably dope these materials. Here, we report the synthesis and spectroscopic analysis of the one-dimensional cuprate Ba$_{2-x}$Sr$_x$CuO$_{3+\delta}$ over a wide range of hole doping. Our angle-resolved photoemission experiments reveal the doping evolution of the holon and spinon branches. We identify a prominent folding branch whose intensity fails to match predictions of the simple Hubbard model. An additional strong near-neighbor attraction, which may arise from coupling to phonons, quantitatively explains experiments for all accessible doping levels. Considering structural and quantum chemistry similarities among cuprates, this attraction will play a similarly crucial role in the high-$T_C$ superconducting counterparts