Checkerboard-type Zhang-Rice States in Overdoped Cuprate Superconductors

TL;DR

This study investigates the evolution of electronic structures in overdoped cuprate superconductors, revealing a checkerboard Zhang-Rice state that challenges existing models and offers new insights into high-temperature superconductivity.

Contribution

It introduces a novel checkerboard-type Zhang-Rice electronic configuration in heavily overdoped cuprates, supported by broadband optical spectroscopy and quantum Monte Carlo simulations.

Findings

Spectral weight redistribution consistent with theoretical models

Identification of a checkerboard Zhang-Rice state in overdoped regime

Persistence of electronic correlations deep into overdoped phase

Abstract

Cuprate superconductors remain central to condensed matter physics due to their technological relevance and unconventional, incompletely understood electronic behavior. While the canonical phase diagram and low-energy models have been shaped largely by studies of underdoped and moderately doped cuprates, the overdoped regime has received comparatively limited attention.Here, we track the evolution of the electronic structure from optimal to heavy overdoping in La2-xSrxCuO4(LSCO) using broadband optical spectroscopy across x=0.15-0.60. The measured spectral changes--including the redistribution of Zhang-Rice-related spectral weigh--are in qualitative agreement with determinant quantum Monte Carlo simulations of the three-orbital Emery model, which together indicate a pronounced reconstruction of the electronic structure beyond hole concentrations x>0.2. Guided by these observations, we propose a spontaneous checkerboard-type Zhang-Rice electronic configuration that captures the coexistence of itinerant and localized carriers characteristic of the heavily overdoped state. Our results refine the doping-dependent Zhang-Rice-based framework for cuprates, illuminate how correlations persist deep into the overdoped regime, and provide new constraints on microscopic mechanisms of high-temperature superconductivity, with broader implications for correlated transition-metal oxides.