Systematic Study of Magnetic Interactions in Insulating Cuprates

TL;DR

This paper systematically investigates magnetic interactions in insulating cuprates, revealing how superexchange and four-spin interactions depend on structure and influence high-energy magnetic excitations.

Contribution

It provides a detailed analysis of superexchange and four-spin interactions in cuprates using small clusters, highlighting their structural dependence and impact on magnetic excitations.

Findings

Superexchange J depends on Cu-O structure via Madelung potential.

A four-spin interaction Jcyc exists with about 10% magnitude of J.

Jcyc significantly affects high-energy magnetic excitations.

Abstract

The magnetic interactions in one-dimensional, two-dimensional (2D) and ladder cuprates are evaluated systematically by using small Cu-O clusters. We find that the superexchange interaction J between nearest neighbor Cu spins strongly depends on Cu-O structure through the Madelung potential, and in 2D and ladder cuprates there is a four-spin interaction Jcyc, with magnitude of 10% of J. We show that Jcyc has a strong influence on the magnetic excitation in the high-energy region of 2D cuprates.