Spin texture in weakly doped $Cu0_2$ planes explaining magnetic correlation length and Raman scattering experiments

TL;DR

This paper presents a magnetic model for weakly doped CuO2 planes that explains magnetic correlation lengths and Raman scattering results, aligning well with experimental data on cuprate superconductors.

Contribution

It introduces a novel magnetic Hamiltonian capturing chiral spin defects caused by holes, providing a unified explanation for magnetic and Raman experimental observations.

Findings

In-plane spin correlation length matches neutron scattering data.

Model explains Raman scattering results in cuprates.

Chiral spin defects influence magnetic properties significantly.

Abstract

A model of $CuO_2$ planes weakly doped with partially delocalised holes is considered. The effect of such a hole on the background AFM spin texture can be represented by a purely magnetic Hamiltonian $H = - \sum_{(ijk)} (\vec S_i \cdot \vec S_j \times \vec S_k)^2$, where the summation is over the four triangles of a single plaquette. We show that this model of randomly distributed chiral spin defects leads to an in--plane spin correlation length approximately described by $\xi^{-1} (x,T) = \xi^{-1} (0,T) + \xi^{-1} (x,0)$, consistent with neutron scattering experiments on $La_{2-x}Sr_xCuO_4$. Further, this model leads to favourable comparisons with $B_{1g}$ Raman scattering results for the same cuprate system.