2011/11/24 by Masahito Mochizuki · 1 citation
Physics and Astronomy · #cond-mat.str-el #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevlett.108.017601
published as Phys. Rev. Lett. 108, 017601 (2012) · 5 pages, 5 figures, accepted for publication in Physical Review Letters
arxiv created 2011/11/24 · arxiv updated 2012/01/09
We theoretically study spin-wave modes and their intense excitations activated by microwave magnetic fields in the skyrmion-crystal phase of insulating magnets by numerically analyzing a two-dimensional spin model using the Landau-Lifshitz-Gilbert equation. Two peaks of spin-wave resonances with frequencies of ~1 GHz are found for in-plane a.c. magnetic field where distribution of the out-of-plane spin components circulates around each skyrmion core. Directions of the circulations are opposite between these two modes, and hence the spectra exhibit salient dependence on the circular polarization of irradiating microwave. A breathing-type mode is also found for out-of-plane a.c. magnetic field. By intensively exciting these collective modes, melting of the skyrmion crystal accompanied by a red shift of the resonant frequency is achieved within nano seconds.