# Colossal electromagnon excitation in the non-cycloidal phase of TbMnO3 under pressure

## TL;DR

This study reveals pressure-induced changes in electromagnon excitations in TbMnO3, showing a disappearance of one electromagnon and a significant increase in another, highlighting potential for advanced magnonic device applications.

## Contribution

It demonstrates how pressure alters electromagnon behavior in TbMnO3, identifying the mechanisms behind different electromagnons and their potential for spin wave control.

## Key findings

- Lower-energy electromagnon disappears under pressure in E-type phase.
- Higher-energy electromagnon intensity increases by an order of magnitude.
- Symmetric exchange-striction mechanism drives the higher-energy electromagnon.

## Abstract

The magnetoelectric coupling, i.e., cross-correlation between electric and magnetic orders, is a very desirable property to combine functionalities of materials for next-generation switchable devices. Multiferroics with spin-driven ferroelectricity presents such a mutual interaction concomitant with magneto- and electro-active excitations called electromagnons. TbMnO3 is a paradigmatic material in which two electromagnons have been observed in the cycloidal magnetic phase. However, their observation in TbMnO3 is restricted to the cycloidal spin phase and magnetic ground states that can support the electromagnon excitation are still under debate. Here, we show by performing Raman spectroscopy measurements under pressure that the lower-energy electromagnon (4 meV) disappears when the ground state enters from a cycloidal phase to an antiferromagnetic phase (E-type). On the contrary, the magnetoelectric activity of the higher-energy electromagnon (8 meV) increases in intensity by one order of magnitude. Using microscopic model calculations, we demonstrate that the lowerenergy electromagnon, observed in the cycloidal phase, originates from a higher harmonic of the magnetic cycloid, and we determine that the symmetric exchange-striction mechanism is at the origin of the higher-energy electromagnon which survives even in the E-type phase. The colossal enhancement of the electromagnon activity in TbMnO3 paves the way to use multiferroics more efficiently for generation, conversion and control of spin waves in magnonic devices.