Dzyaloshinsky-Moriya antisymmetric exchange coupling in cuprates: Oxygen effects

TL;DR

This paper investigates the role of oxygen in Dzyaloshinsky-Moriya antisymmetric exchange coupling in cuprates, highlighting local contributions, experimental probes, and predicted magnetic effects in specific chain structures.

Contribution

It provides a detailed analysis of oxygen's influence on Dzyaloshinsky-Moriya coupling and predicts new magnetic phenomena in cuprate chains.

Findings

Oxygen contributions can compete with copper in Dzyaloshinsky-Moriya vectors.

Intermediate oxygen Knight shift effectively probes Dzyaloshinsky-Moriya effects.

Predicted strong oxygen weak antiferromagnetism in CuO$_2$ chains.

Abstract

We revisit a problem of Dzyaloshinsky-Moriya antisymmetric exchange coupling for a single bond in cuprates specifying the local spin-orbital contributions to Dzyaloshinsky vector focusing on the oxygen term. The Dzyaloshinsky vector and respective weak ferromagnetic moment is shown to be a superposition of comparable and, sometimes, competing local Cu and O contributions. The intermediate oxygen $^{17}$O Knight shift is shown to be an effective tool to inspect the effects of Dzyaloshinsky-Moriya coupling in an external magnetic field. We predict the effect of $strong$ oxygen weak antiferromagnetism in edge-shared CuO$_2$ chains due to uncompensated oxygen Dzyaloshinsky vectors. Finally, we revisit the effects of symmetric spin anisotropy, in particular, those directly induced by Dzyaloshinsky-Moriya coupling.