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arXiv · 2006.08219

Femtosecond laser pulse driven caustic spin wave beams

S. Muralidhar·R. Khymyn·A. A. Awad·A. Alemán·D. Hanstorp·J. Åkerman·.
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Abstract

Controlling the directionality of spin waves is a key ingredient in wave-based computing methods such as magnonics. In this paper, we demonstrate this particular aspect by using an all-optical point-like source of continuous spin waves based on frequency comb rapid demagnetization. The emitted spin waves contain a range of k-vectors and by detuning the applied magnetic field slightly off the ferromagnetic resonance (FMR), we observe X-shaped caustic spin-wave patterns at $70^{\circ}$ propagation angles as predicted by theory. When the harmonic of the light source approaches theFMR, the caustic pattern gives way to uniaxial spin-wave propagation perpendicular to the in-plane component of the applied field. This field-controlled propagation pattern and directionality of optically emitted short-wavelength spin waves provide additional degrees of freedom when designing magnonic devices.

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S. Muralidhar, R. Khymyn, A. A. Awad, A. Alemán, D. Hanstorp, J. Åkerman, .. 2020-06-15. Femtosecond laser pulse driven caustic spin wave beams. https://doi.org/10.1103/physrevlett.126.037204

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