# Unravelling local spin polarization of Zhang-Rice singlet in lightly hole-doped cuprates using high-energy optical conductivity

## TL;DR

This study reveals strong local spin polarization and ferromagnetic correlations near doped holes in lightly hole-doped cuprates, using high-energy optical conductivity measurements up to 35 eV to uncover magnetic and electronic correlations.

## Contribution

It introduces a novel approach using high-energy optical conductivity to probe local magnetic correlations in hole-doped cuprates, supported by theoretical calculations.

## Key findings

- Strong spin polarization observed near doped holes.
- Anomaly at ~25 K linked to magnetic stripe phase.
- Identification of high-energy optical transitions and their temperature dependence.

## Abstract

Unrevealing local magnetic and electronic correlations in the vicinity of charge carriers is crucial in order to understand rich physical properties in correlated electron systems. Here, using high-energy optical conductivity (up to 35 eV) as a function of temperature and polarization, we observe a surprisingly strong spin polarization of the local spin singlet with enhanced ferromagnetic correlations between Cu spins near the doped holes in lightly hole-doped La$_{1.95}$Sr$_{0.05}$Cu$_{0.95}$Zn$_{0.05}$O$_{4}$. The changes of the local spin polarization manifest strongly in the temperature-dependent optical conductivity at ~7.2 eV, with an anomaly at the magnetic stripe phase (~25 K), accompanied by anomalous spectral-weight transfer in a broad energy range. Supported by theoretical calculations, we also assign high-energy optical transitions and their corresponding temperature dependence, particularly at ~2.5 ~8.7, ~9.7, ~11.3 and ~21.8 eV. Our result shows the importance of a strong mixture of spin singlet and triplet states in hole-doped cuprates and demonstrates a new strategy to probe local magnetic correlations using high- energy optical conductivity in correlated electron systems.

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Source: https://tomesphere.com/paper/1704.02452