Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 31: Poster II

MA 31.35: Poster

Wednesday, March 19, 2025, 17:00–19:30, P1

All-Magnonic Frequency Multiplication in Ferromagnetic Microstructures — •Alexandra Schrader¹, Chris Körner¹, Rouven Dreyer¹, Niklas Liebing², and Georg Woltersdorf¹ — ¹Martin-Luther-Universität Halle-Wittenberg — ²Fraunhofer Institute for Electronic Nano Systems ENAS, Chemnitz

We have observed all-magnetic frequency multiplication and a six-octave frequency comb in polycrystalline NiFe thin films [1]. At low bias fields, magnetic ripples cause local magnetization tilting, and MHz-range excitation induces rapid switching and high-harmonic spin wave emission. To enable practical applications, it is essential to miniaturize active components and optimize the frequency multiplication efficiency, aiming to generate GHz-range spin waves using MHz rf excitation in minimal-sized elements.

Recently, frequency multiplication has also been observed in extended CoFeB layers [2]. This motivates us to investigate the effect in both thin films as well as microstructures of CoFeB. Using micromagnetic simulations, we analyze how various parameters - such as saturation magnetization, anisotropy, static bias field and the shape, size and thickness of micrometer-sized CoFeB elements - influence generation efficiency. These numerical results are then compared to experimental measurements performed via NV magnetometry and SNS-MOKE techniques on actual samples.

[1] Koerner et al., Science 375, 6585 (2022)

[2] Wu et al., npj Spintronics 2, 30 (2024)

Keywords: magnonics; frequency conversion; nonlinear spinwaves; microstructures; magnetic imaging