Tunable quasi-discrete spectrum of spin waves excited by periodic laser patterns

Abstract

We present a concept for selective excitation of magnetostatic surface waves with a quasi-discrete spectrum using spatially patterned femtosecond laser pulses inducing either an ultrafast change of magnetic anisotropy or an inverse Faraday effect. We micromagnetically simulate the excitation of the waves with a periodically patterned uni- or bipolar laser impact. Such excitation yields multiple wavepackets propagating with different group velocities, whose dispersion corresponds to the set of quasi-discrete points. In addition, we show that the frequency of the spectral peaks can be controlled by the polarity of the periodic impact and its spatial period. The presented consideration of multiple spatially periodic magnetostatic surface wave sources as a whole enables implementation of a comprehensive toolkit of spatiotemporal optical methods for tunable excitation and control of spin-wave parameters.