Regensburg 2019 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 8: Magnonics

MA 8.3: Vortrag

Montag, 1. April 2019, 15:30–15:45, H52

Phase-resolved imaging of non-linear spin-wave excitation at low magnetic bias field — •Rouven Dreyer, Lea Apel, Niklas Liebing, and Georg Woltersdorf — Martin Luther University Halle-Wittenberg, Institute of Physics, Von-Danckelmann-Platz 3, 06120 Halle (Saale), Germany

Recently it was shown that the prediction of the non-linear spin-wave excitation in the framework of Suhl instability processes is not adequate at low magnetic bias fields. In particular, it was shown by spatially averaged and time-resolved x-ray ferromagnetic resonance spectroscopy that in the low field regime non-linear spin waves are excited parametrically at 3/2 of the excitation frequency [1].

Here we demonstrate the 3/2 ω non-linear spin-wave (NLSW) excitation in Ni₈₀Fe₂₀ microstructures using time-resolved table-top magneto-optical microscopy. We have developed a novel variant of scanning magneto-optical microscopy which we term super-Nyquist sampling microscopy (SNS-MOKE) [2]. This technique allows for phase-resolved imaging of the sample at arbitrary frequencies. In this way we detect the parametrically excited NLSWs at 3/2 ω of the excitation frequency in space and time directly. The corresponding wave vectors obtained from the two dimensional Fourier transformation of the observed spin-wave pattern at 3/2 ω and higher harmonics are in agreement with the theoretical predictions from Bauer et al. [1].

[1] H. G. Bauer et al., Nat. Commun. 6:8274 (2015)

[2] R. Dreyer et al., arXiv:1803.04943 [cond-mat.mes-hall] (2018)