Magnetic structure of CuCrO2: a single crystal neutron diffraction study

TL;DR

This study uses single crystal neutron diffraction to elucidate the magnetic structures of CuCrO2 across two phase transitions, revealing a 3D proper screw structure at low temperatures and 2D order at intermediate temperatures, clarifying the conditions for multiferroicity.

Contribution

It provides the first detailed determination of the magnetic structure of CuCrO2 across its phase transitions using neutron diffraction.

Findings

Low-temperature magnetic structure is a 3D proper screw.

Between transitions, magnetic order is essentially 2D.

Multiferroic state exists only in the 3D magnetic phase.

Abstract

This paper presents results of a recent study of multiferroic \CCO\ by means of single crystal neutron diffraction. This system has two close magnetic phase transitions at $T\nsub{N1}=24.2$ K and $T\nsub{N2}=23.6$ K. The low temperature magnetic structure below $T\nsub{N2}$ is unambiguously determined to be a fully 3-dimensional proper screw. Between $T\nsub{N1}$ and $T\nsub{N2}$ antiferromagnetic order is found that is essentially 2-dimensional. In this narrow temperature range, magnetic near neighbor correlations are still long range in the ($H,K$) plane, whereas nearest neighbors along the $L$-direction are uncorrelated. Thus, the multiferroic state is realized only in the low-temperature 3-dimensional state and not in the 2-dimensional state.