Hybrid paramagnon phonon modes at elevated temperatures in EuTiO3

TL;DR

This paper reports the discovery of hybrid magnon-phonon modes in EuTiO3 at high temperatures, revealing strong magneto-dielectric coupling that could influence future material design and applications.

Contribution

It demonstrates the existence of hybrid paramagnon-phonon modes in EuTiO3 at elevated temperatures through experimental and theoretical evidence.

Findings

Hybrid magnon-phonon modes observed at high temperatures.

Strong magneto-dielectric effects evidenced in EuTiO3.

Coupled spin-polarizability Hamiltonian explains the mode hybridization.

Abstract

EuTiO3 (ETO) has recently experienced an enormous revival of interest because of its possible multiferroic properties which are currently in the focus of research. Unfortunately ETO is an unlikely candidate for enlarged multifunctionality since the mode softening - typical for ferroelectrics - remains incomplete, and the antiferromagnetic properties appear at 5.5K only. However, a strong coupling between lattice and Eu spins exists and leads to the appearance of a magnon-phonon-hybrid mode at elevated temperatures as evidenced by electron paramagnetic resonance (EPR), muon spin rotation ({\mu}SR) experiments and model predictions based on a coupled spin-polarizability Hamiltonian. This novel finding supports the notion of strong magneto-dielectric (MD) effects being realized in ETO and opens new strategies in material design and technological applications.