Spin-lattice coupling, frustration and magnetic order in multiferroic RMnO3

TL;DR

This study investigates the magneto-elastic coupling and magnetic structures in multiferroic RMnO3 compounds using neutron scattering, revealing how atomic positions influence magnetic interactions across different rare-earth ions.

Contribution

It provides the first comprehensive analysis linking atomic positions, magnetic order, and spin dynamics in RMnO3, highlighting the role of Mn ion positioning in magnetic coupling.

Findings

Strong magneto-elastic coupling observed across all compounds.

Atomic positions correlate with magnetic structure and spin wave properties.

Mn ion position relative to 1/3 threshold determines inter-plane magnetic coupling.

Abstract

We have performed high resolution neutron diffraction and inelastic neutron scattering experiments in the frustrated multiferroic hexagonal compounds RMnO3 (R=Ho, Yb, Sc, Y), which provide evidence of a strong magneto-elastic coupling in the the whole family. We can correlate the atomic positions, the type of magnetic structure and the nature of the spin waves whatever the R ion and temperature. The key parameter is the position of the Mn ions in the unit cell with respect to a critical threshold of 1/3, which determines the sign of the coupling between Mn triangular planes.