Magnetic field induced dehybridization of the electromagnons in multiferroic TbMnO3

TL;DR

This study investigates how magnetic fields influence electromagnon excitations in TbMnO3, revealing their transformation into antiferromagnetic modes and spectral weight transfer, with insights into the role of Mn-O distances in ferroelectricity.

Contribution

It provides new experimental evidence on magnetic field effects on electromagnons and identifies the Mn-O distance as crucial for their polar character.

Findings

Electromagnons become pure antiferromagnetic modes under magnetic field.

Spectral weight shifts from electromagnons to magnons during phase transition.

A new electromagnon resonance is detected along the b axis.

Abstract

We have studied the impact of the magnetic field on the electromagnon excitations in TbMnO3 crystal. Applying magnetic field along the c axis, we show that the electromagnons transform into pure antiferromagnetic modes, losing their polar character. Entering in the paraelectric phase, we are able to track the spectral weight transfer from the electromagnons to the magnon excitations and we discuss the magnetic excitations underlying the electromagnons. We also point out the phonons involved in the phase transition process. This reveals that the Mn-O distance plays a key role in understanding the ferroelectricity and the polar character of the electromagnons. Magnetic field measurements along the b axis allow us to detect a new electromagnon resonance in agreement with a Heisenberg model.