Optical excitation of propagating magnetostatic waves in an epitaxial Galfenol film by an ultrafast magnetic anisotropy change

Abstract

Using a time-resolved optically-pumped scanning optical microscopy technique we demonstrate the laser-driven excitation and propagation of spin waves in a 20-nm film of a ferromagnetic metallic alloy Galfenol epitaxially grown on a GaAs substrate. In contrast to previous all-optical studies of spin waves we employ laser-induced thermal changes of magnetocrystalline anisotropy as an excitation mechanism. A tightly focused 70-fs laser pulse excites packets of magnetostatic surface waves with a $e^{-1}$ propagation length of 3.4 $\mu$m, which is comparable with that of permalloy. As a result, laser-driven magnetostatic spin waves are clearly detectable at distances up to 10 $\mu$m, which promotes epitaxial Galfenol films to the limited family of materials suitable for magnonic devices. A pronounced in-plane magnetocrystalline anisotropy of the Galfenol film offers an additional degree of freedom for manipulating the spin waves' parameters. Reorientation of an in-plane external magnetic field relative to the crystallographic axes of the sample tunes the frequency, amplitude and propagation length of the excited waves.

arXiv comment10 pages, 5 figures, original article, revised version from 20 Aug 2019

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Cited by in corpus (10)

• An Introduction to Spin Wave Computing
• Effect of magnetic anisotropy relaxation on laser-induced magnetization precession in thin galfenol films
• Observation of evanescent spin waves in the magnetic dipole regime
• Spectrum evolution and chirping of laser-induced spin wave packets in thin iron films
• Laser-induced magnetization precession in individual magnetoelastic domains of a multiferroic CoFeB/BaTiO${}_3$ composite
• Resonant thermal energy transfer to magnons in a ferromagnetic nanolayer
• Néel domain wall as a tunable filter for optically excited magnetostatic waves
• Unidirectional propagation of spin waves excited by femtosecond laser pulses in a planar waveguide
• Nonreciprocal collective magnetostatic wave modes in geometrically asymmetric bilayer structure with nonmagnetic spacer
• Transition magnon modes in thin ferromagnetic nanogratings