Raman scattering from phonons and magnons in RFe3)BO3)4

TL;DR

This study uses Raman scattering to investigate phonons and magnons in RFe3(BO3)4 compounds, revealing phase transitions, magnetic ordering, and strong lattice-magnetic coupling with persistent high-temperature correlations.

Contribution

It provides new insights into the coupling between lattice and magnetic properties and details the sequence of phase transitions in RFe3(BO3)4 materials.

Findings

Identification of structural and magnetic phase transitions.

Observation of suppressed low-energy magnetic scattering after Fe-sublattice ordering.

Detection of persistent short-range magnetic correlations at high temperatures.

Abstract

Inelastic light scattering spectra of several members of the RFe3(BO3)4 family reveal a cascade of phase transitions as a function of temperature, starting with a structural, weakly first order, phase transition followed by two magnetic phase transitions. Those consist of the ordering of the Fe-spin sublattice revealed by all the compound, and a subsequent spin-reorientational transition for GdFe3(BO3)4. The Raman data evidence a strong coupling between the lattice and magnetic degrees of freedom in these borates. The Fe-sublattice ordering leads to a strong suppression of the low energy magnetic scattering, and a multiple peaked two-magnon scattering continuum is observed. Evidence for short-range correlations is found in the `paramagnetic' phase by the observation of a broad magnetic continuum in the Raman data, which persists up to surprisingly high temperatures.