Coupling of phonons and electromagnons in GdMnO_3

TL;DR

This study investigates the coupling between phonons and electromagnons in GdMnO_3, revealing strong magnetoelectric effects and phase-dependent electromagnon activity influenced by temperature and magnetic field.

Contribution

It provides new insights into the phase-dependent magnetoelectric coupling and phonon-electromagnon interactions in GdMnO_3, highlighting the transfer of spectral weight between excitations.

Findings

Strong magnetodielectric effects in the incommensurate phase

Suppression of electromagnons in the canted antiferromagnetic phase

Spectral weight transfer to lattice vibrations

Abstract

The infrared and Terahertz properties of GdMnO_3 have been investigated as function of temperature and magnetic field, with special emphasis on the phase boundary between the incommensurate and the canted antiferromagnetic structures. The heterogeneous incommensurate phase reveals strong magnetodielectric effects, characterized by significant magnetoelectric contributions to the static dielectric permittivity and by the existence of electrically excited magnons (electromagnons). In the commensurate canted antiferromagnetic phase the magnetoelectric contributions to the dielectric constant and electromagnons are suppressed. The corresponding spectral weight is transferred to the lowest lattice vibration demonstrating the strong coupling of phonons with electromagnons.