Distinct Optical Excitation Mechanisms of a Coherent Magnon in a van der Waals Antiferromagnet

Abstract

The control of antiferromagnets with ultrashort optical pulses has emerged as a prominent field of research. Tailored laser excitation can launch coherent spin waves at terahertz frequencies, yet a comprehensive description of their generation mechanisms is still lacking despite extensive efforts. Using terahertz emission spectroscopy, we investigate the generation of a coherent magnon mode in the van der Waals antiferromagnet NiPS${}_3$ under a range of photoexcitation conditions. By tuning the pump photon energy from transparency to resonant with a $d$-$d$ transition, we reveal a striking change in the coherent magnon's dependence on the pump polarization, indicating two distinct excitation mechanisms. Our findings provide a strategy for the manipulation of magnetic modes via photoexcitation around sub-gap electronic states.

17 pages, 16 figures

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Cited by in corpus (3)

• Probing the band structure of the strongly correlated antiferromagnet NiPS3 across its phase transition
• Ultrafast Dynamics of Spin-Orbit Entangled Excitons Coupled to Magnetic Ordering in van der Waals Antiferromagnet NiPS3
• Optically induced magnetic inertia and magnons from non-Markovian extension of the Landau-Lifshitz-Gilbert equation