Impulsive Fermi magnon-phonon resonance in antiferromagnetic $CoF_{2}$

TL;DR

This paper demonstrates the experimental realization of Fermi magnon-phonon resonance in antiferromagnetic CoF2 using terahertz pulses and magnetic fields, revealing impulsive nonlinear spin-lattice interactions and energy transfer mechanisms.

Contribution

It introduces the first experimental observation of Fermi magnon-phonon resonance in antiferromagnetic CoF2 and explores the nonlinear dynamics of spin-lattice coupling under intense THz excitation.

Findings

Observation of impulsive THz-induced magnon-phonon response

Identification of energy transfer at Fermi resonance conditions

Insights into controlling coherent magnon-phonon interactions

Abstract

Understanding spin-lattice interactions in antiferromagnets is one of the most fundamental issues at the core of the recently emerging and booming fields of antiferromagnetic spintronics and magnonics. Recently, coherent nonlinear spin-lattice coupling was discovered in an antiferromagnet which opened the possibility to control the nonlinear coupling strength and thus showing a novel pathway to coherently control magnon-phonon dynamics. Here, utilizing intense narrow band terahertz (THz) pulses and tunable magnetic fields up to 7 T, we experimentally realize the conditions of the Fermi magnon-phonon resonance in antiferromagnetic $CoF_{2}$. These conditions imply that both the spin and the lattice anharmonicities harvest energy transfer between the subsystems, if the magnon eigenfrequency $f_{m}$ is twice lower than the frequency of the phonon $2f_{m}=f_{ph}$. Performing THz pump-infrared probe spectroscopy in conjunction with simulations, we explore the coupled magnon-phonon dynamics in the vicinity of the Fermi-resonance and reveal the corresponding fingerprints of an impulsive THz-induced response. This study focuses on the role of nonlinearity in spin-lattice interactions, providing insights into the control of coherent magnon-phonon energy exchange.