%0 Journal Article
%K Laser spectroscopy
%K Excited states
%K Applied magnetic fields
%K Collective modes
%K Gilbert damping
%K Helical state
%K Itinerant magnets
%K Lower frequencies
%K Magnetic excitations
%K Time-resolved optical spectroscopy
%K Time-resolved spectroscopy
%K Damping
%A J.D Koralek
%A D Meier
%A J.P Hinton
%A A Bauer
%A S.A Parameswaran
%A A Vishwanath
%A Ramamoorthy Ramesh
%A R.W Schoenlein
%A C Pfleiderer
%A J Orenstein
%B Physical Review Letters
%D 2012
%G eng
%R 10.1103/PhysRevLett.109.247204
%T Observation of coherent helimagnons and gilbert damping in an itinerant magnet
%V 109
%X 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.