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arXiv · 2402.17041

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

Clifford J. Allington·Carina A. Belvin·Urban F. P. Seifert·Mengxing Ye·Tommy Tai·Edoardo Baldini·Suhan Son·Junghyun Kim·Jaena Park·Je-Geun Park·Leon Balents·Nuh Gedik
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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.

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Clifford J. Allington, Carina A. Belvin, Urban F. P. Seifert, Mengxing Ye, Tommy Tai, Edoardo Baldini, Suhan Son, Junghyun Kim, Jaena Park, Je-Geun Park, Leon Balents, Nuh Gedik. 2025-02-12. Distinct Optical Excitation Mechanisms of a Coherent Magnon in a van der Waals Antiferromagnet. https://doi.org/10.1103/physrevlett.134.066903

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