Zig-zag ladders with staggered magnetic chirality in S = 3/2 compound beta-CaCr2O4

TL;DR

This study investigates the magnetic structures of beta-CaCr2O4, revealing complex antiferromagnetic ordering with staggered chiralities in a S=3/2 compound, driven by unique lattice topology and Dzyaloshinskii-Moriya interactions.

Contribution

It uncovers the magnetic ordering and staggered chiralities in beta-CaCr2O4, linking lattice topology to complex magnetic phenomena not previously characterized in this compound.

Findings

Identification of two magnetic regimes between 21K and 270K.

Observation of incommensurate antiferromagnetic order below 21K.

Detection of staggered chiralities explained by Dzyaloshinskii-Moriya interactions.

Abstract

The crystal and magnetic structures of the S = 3/2 chain antiferromagnet beta-CaCr2O4 have been investigated by means of specific heat, magnetization, muon relaxation and neutron powder diffraction between 300K and 1.5K. Owing to the original topology of the Cr3+ magnetic lattice, which can be described as a network of triangular ladders, equivalent to chains with nearest and next-nearest neighbors interactions, evolution of the magnetic scattering intensity in this compound evidences two magnetic regimes : for 21K < T < 270K, a low-dimensionality magnetic ordering of the Cr3+ spins is observed, simultaneously with a strong contraction of the ladder legs, parallel to c. Below TN = 21K, a complex antiferromagnetic ordering is evidenced, with an incommensurate propagation vector k = (0, 0, q) (q ~ 0.477 at 1.5K), as exchange interactions between ladders become significant. This complex magnetic ordering can be described as a honeycomb-like arrangement of cycloids, running along c, with staggered chiralities. The experimental observation of this staggered chirality can be understood by taking into account antisymmetric Dzyaloshinskii-Moriya exchange terms.