Strong spin triplet contribution of the first removal state in the insulating regime of Bi2Sr2Ca1-xYxCu2O8+delta

TL;DR

This study reveals a unique spin triplet contribution in the first removal state of Bi2Sr2Ca1-xYxCu2O8+delta, differing from other cuprates, and introduces a new triplet state model to explain the experimental dispersion.

Contribution

It proposes a novel triplet counterpart to the Zhang-Rice singlet state, extending the 3-band pd-model for cuprate superconductors.

Findings

Unconventional three-peak structure in the dispersion data.

Significant spin triplet contribution in the first removal state.

Deviation from typical cuprate dispersion patterns.

Abstract

The experimental dispersion of the first removal state in the insulating regime of Bi2Sr2Ca1-xYxCu2O8+delta is found to differ significantly from that of other parent materials: oxyclorides and La2CuO4 . For Y-contents of 0.92 > x > 0.55 due to nonstoichiometric effects in the Bi-O layers, the hole concentration in the CuO2 -layers is almost constant and on the contrary the crystal lattice parameters a,b,c change very strongly. This (a,b) parameter increase and c parameter decrease results in an unconventional three peak structure at (0,0);(pi/2, pi/2);(pi,pi) for x=0.92. We can describe the experimental data only beyond the framework of the 3-band pd-model involving the representations of a new triplet counterpart for the Zhang-Rice singlet state.