Coherent strong-coupling of terahertz magnons and phonons in a Van der Waals antiferromagnetic insulator

Abstract

Emergent cooperative motions of individual degrees of freedom, i.e. collective excitations, govern the low-energy response of system ground states under external stimulations and play essential roles for understanding many-body phenomena in low-dimensional materials. The hybridization of distinct collective modes provides a route towards coherent manipulation of coupled degrees of freedom and quantum phases. In magnets, strong coupling between collective spin and lattice excitations, i.e., magnons and phonons, can lead to coherent quasi-particle magnon polarons. Here, we report the direct observation of a series of terahertz magnon polarons in a layered zigzag antiferromagnet FePS3 via far-infrared (FIR) transmission measurements. The characteristic avoided-crossing behavior is clearly seen as the magnon-phonon detuning is continuously changed via Zeeman shift of the magnon mode. The coupling strength g is giant, achieving 120 GHz (0.5 meV), the largest value reported so far. Such a strong coupling leads to a large ratio of g to the resonance frequency (g/ω) of 4.5%, and a value of 29 in cooperativity (g^2/γ_{ph}γ_{mag}). Experimental results are well reproduced by first-principle calculations, where the strong coupling is identified to arise from phonon-modulated anisotropic magnetic interactions due to spin-orbit coupling. These findings establish FePS3 as an ideal testbed for exploring hybridization-induced topological magnonics in two dimensions and the coherent control of spin and lattice degrees of freedom in the terahertz regime.

References in corpus (21)

• Gate-tuning of graphene plasmons revealed by infrared nano-imaging
• Optical nano-imaging of gate-tuneable graphene plasmons
• Strong light-matter coupling in two-dimensional atomic crystals
• Ising-Type Magnetic Ordering in Atomically Thin FePS3
• Electronic and magnetic properties of single-layer MPX${}_3$ metal phosphorous trichalcogenides
• Room temperature Tamm-Plasmon Exciton-Polaritons with a WSe2 monolayer
• Order by distortion and string modes in pyrochlore antiferromagnet
• Magnon Polarons in the Spin Seebeck Effect
• Half-magnetization plateau stabilized by structural distortion in the antiferromagnetic Heisenberg model on a pyrochlore lattice
• Thermal Hall Effect Induced by Magnon-Phonon Interactions
• Coherent elastic excitation of spin waves
• Quasi-Two-Dimensional Magnon Identification in Antiferromagnetic FePS3 via Magneto-Raman Spectroscopy
• Topological Magnon-Phonon Hybrid Excitations in Two-Dimensional Ferromagnets with Tunable Chern Numbers
• Magnon polaron formed by selectively coupled coherent magnon and phonon modes of a surface patterned ferromagnet
• SU(3) Topology of Magnon-Phonon Hybridization in 2D Antiferromagnets
• Chiral Phonon Transport Induced by Topological Magnons
• Peierls-like transition induced by frustration in a two-dimensional antiferromagnet
• Topological Magnetoelastic Excitations in Non-Collinear Antiferromagnets
• Observation of magnon-polarons in a uniaxial antiferromagnetic insulator
• Magnon-phonon coupling and two-magnon continuum in two-dimensional triangular antiferromagnet CuCrO2
• Evidence for magnon-phonon coupling in the topological magnet Cu${}_3$TeO${}_6$

Cited by in corpus (6)

• Tunable Exciton-Hybridized Magnon Interactions in a Layered Semiconductor
• Chirality selective magnon-phonon hybridization and magnon-induced chiral phonons in a layered zigzag antiferromagnet
• Terahertz field-induced metastable magnetization near criticality in FePS3
• Spin Dynamics in van der Waals Magnetic Systems
• Identifying band structure changes of FePS3 across the antiferromagnetic phase transition
• High-angular momentum excitations in collinear antiferromagnet FePS${}_3$