Discovery of terahertz-frequency orbitally coupled magnons in a kagome ferromagnet.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40614204.
- Also identified by DOI 10.1126/sciadv.adw1182 and PMC identifier 12227069.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
In ferromagnetic materials, magnons-quanta of spin waves-typically resonate in the gigahertz range. Beyond conventional magnons, while theoretical studies have predicted magnons associated with orbital magnetic moments, their direct observation has remained challenging. Here, we present the discovery of two distinct terahertz orbitally coupled magnon resonances in the topological kagome ferromagnet Co<sub>3</sub>Sn<sub>2</sub>S<sub>2</sub>. Using time-resolved Kerr rotation spectroscopy, we pinpoint two magnon resonances at 0.61 and 0.49 terahertz at 6 kelvin, surpassing all previously reported magnon resonances in ferromagnets due to strong magnetocrystalline anisotropy. These dual modes originate from the strong coupling of localized spin and orbital magnetic moments. These findings unveil an unconventional category of magnons in a ferromagnet stemming from orbital magnetic moments and position Co<sub>3</sub>Sn<sub>2</sub>S<sub>2</sub> as a promising candidate for high-speed terahertz spintronic applications.