Quantum spin chains with frustration due to Dzyaloshinskii-Moriya interactions

TL;DR

This paper investigates two quantum spin chain materials with Dzyaloshinskii-Moriya interactions, revealing how their unique frustration effects influence their magnetic phase diagrams through experimental techniques.

Contribution

It demonstrates the presence of uniform but antiparallel Dzyaloshinskii-Moriya interactions in two compounds, leading to a novel type of inter-chain frustration.

Findings

Substantial Dzyaloshinskii-Moriya interactions identified

Inter-chain frustration causes unusual phase diagrams

Experimental techniques confirm the magnetic hierarchy

Abstract

The properties of two quantum spin chain materials, K$_2$CuSO$_4$Cl$_2$ and K$_2$CuSO$_4$Br$_2$, are studied by a variety of experimental techniques, including bulk measurements, neutron spectroscopy and ESR. The hierarchy of relevant terms in the magnetic Hamiltonian is established. It is shown that these two compounds feature substantial Dzyaloshinskii-Moriya (DM) interactions that are uniform within each chain, but antiparallel in adjacent chains. The result is a peculiar type of frustration of inter-chain interactions, which leads to an unusual field-temperature phase diagram.