Fast pulse-excited spin waves in yttrium iron garnet thin films

Abstract

Fast pulse-driven spin-wave excitations in magnetic films have been studied experimentally and theoretically. The experiment was conducted on a low loss yttrium iron garnet thin-film strip with separate microstrip lines for excitation and detection. The theoretical analysis was based on the full spatio-temporal Fourier response of the input pulse/microstrip line configuration and the spin-wave dispersion for the film. The data and analysis provide a clear and precise picture of the manner in which the fast pulse-excited spin-wave signals are defined and controlled by the interplay of pulse rise time, excitation geometry, and spin-wave dispersion. The amplitude of the spin-wave wave packet associated with the leading or trailing edges of the drive decreases with the pulse rise time and the static magnetic field, and increases with the pulse amplitude. The spectral profile of the spin-wave excitation is highly asymmetric, with a steep lower-frequency edge and a gradual upper-frequency edge. The spectral bands are controllable; an increase in the static magnetic field pushes up the lower cutoff frequency, while an increase in the pulse rise time pushes down the higher cutoff frequency.