Myriad of Terahertz Magnons with All-Optical Magnetoelectric Functionality for Efficient Spin-Wave Computing in Honeycomb Magnet Co4Ta2O9

TL;DR

This paper uncovers a rich spectrum of terahertz magnons and hybrid modes in Co4Ta2O9, demonstrating their potential for ultrafast, all-optical spin-wave computing with magnetoelectric control.

Contribution

It reveals a diverse set of THz magnons and hybrid modes in Co4Ta2O9, linking structural, magnetic, and dielectric properties for advanced spin-wave device applications.

Findings

Unveiled ten excitation modes, including magnons and hybrid magnon-phonon modes.

Identified a THz magnetoelectric effect linked to spin-lattice interactions.

Demonstrated magnetic field control over spin excitations.

Abstract

Terahertz (THz) magnonics represent the notion of mathematical algebraic operations of magnons such as addition and subtraction in THz regime which is an emergent dissipationless ultrafast alternative to existing data processing technologies. Spin waves on antiferromagnets with a twist in spin order host such magnons in THz regime, which possess advantage of higher processing speeds, additional polarization degree of freedom and longer propagation lengths compared to that of gigahertz magnons in ferromagnets. While interaction among THz magnons is the crux of algebra operations, it requires magnetic orders with closely spaced magnon modes for easier experimental realization of their interactions. Herein, rich wealth of magnons spanning a narrow energy range of 0.4 to 10 meV is unraveled in Co4Ta2O9 using magneto-THz spectroscopy. Rare multitude of ten excitation modes, either of magnons or hybrid magnon-phonon modes is presented. Among other attributes, spin lattice interaction suggests a correlation among spin and local lattice distortion, magnetostriction, and magnetic exchange interaction signifying a THz magnetoelectric effect. This unification of structural, magnetic and dielectric facets, and their magnetic field control in a narrow spectrum unwinds the mechanism underneath the system's complexity while the manifestation of multitude of spin excitation modes is a potential source to design multiple channels in spin-wave computing based devices.