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arXiv · 2311.06186

Nonreciprocal Spin Waves in Nanoscale Domain Walls Detected by Scanning X-ray Microscopy in Perpendicular Magnetic Anisotropic Fe/Gd Multilayers

Ping Che·Axel Deenen·Andrea Mucchietto·Joachim Grafe·Michael Heigl·Korbinian Baumgaertl·Markus Weigand·Michael Bechtel·Sabri Koraltan·Gisela Schutz·Dieter Suess·Manfred Albrecht·Dirk Grundler
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Abstract

Spin wave nonreciprocity in domain walls (DWs) allows for unidirectional signal processing in reconfigurable magnonic circuits. Using scanning transmission x-ray microscopy (STXM), we examined coherently-excited magnons propagating in Bloch-like DWs in amorphous Fe/Gd multilayers with perpendicular magnetic anisotropy (PMA). Near 1 GHz we detected magnons with short wavelengths down to $\lambda = 281$ nm in DWs whose minimum width amounted to $\delta_{\rm DW} = 52$ nm. Consistent with micromagnetic simulations, the STXM data reveal their nonreciprocal magnon band structures. We identified Bloch points which disrupted the phase evolution of magnons and induced different $\lambda$ adjacent to the topological defects. Our observations provide direct evidence of nonreciprocal spin waves within Bloch-like DWs, serving as programmable waveguides in magnonic devices with directed information flow.

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Ping Che, Axel Deenen, Andrea Mucchietto, Joachim Grafe, Michael Heigl, Korbinian Baumgaertl, Markus Weigand, Michael Bechtel, Sabri Koraltan, Gisela Schutz, Dieter Suess, Manfred Albrecht, Dirk Grundler. 2023-11-10. Nonreciprocal Spin Waves in Nanoscale Domain Walls Detected by Scanning X-ray Microscopy in Perpendicular Magnetic Anisotropic Fe/Gd Multilayers. https://doi.org/10.1002/adma.202508181

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