Publication Type:Journal Article
Source:Physical Review Letters, Volume 109, Number 24 (2012)
Keywords:Applied magnetic fields, Collective modes, Damping, Excited states, Gilbert damping, Helical state, Itinerant magnets, Laser spectroscopy, Lower frequencies, Magnetic excitations, Time-resolved optical spectroscopy, Time-resolved spectroscopy
We study the magnetic excitations of itinerant helimagnets by applying time-resolved optical spectroscopy to Fe0.8Co0.2Si. Optically excited oscillations of the magnetization in the helical state are found to disperse to lower frequency as the applied magnetic field is increased; the fingerprint of collective modes unique to helimagnets, known as helimagnons. The use of time-resolved spectroscopy allows us "format"to address the fundamental magnetic relaxation processes by directly measuring the Gilbert damping, revealing the versatility of spin dynamics in chiral magnets. © 2012 American Physical Society.
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