Direct Observation of Worm‐Like Nanochannels and Emergent Magnon Motifs in Artificial Ferromagnetic Quasicrystals. (15th July 2020)

• Record Type: Journal Article
• Authors: Watanabe, Sho; Bhat, Vinayak S.; Baumgaertl, Korbinian; Grundler, Dirk
• Is Part Of: Advanced functional materials. Volume 30:Number 36(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-07-15
• Subjects: magnonics -- metamaterials -- nanomagnets -- quasicrystals -- spin waves; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202001388
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Quasicrystalline structures and aperiodic metamaterials find applications ranging from established consumer gadgets to potential high‐tech photonic components owing to both complex arrangements of constituents and exotic rotational symmetries. Magnonics is an evolving branch of magnetism research where information is transported via magnetization oscillations (magnons). Their control and manipulation are so far best accomplished in periodic metamaterials which exhibit properties artificially modulated on the nanoscale. They give rise to functional components, such as band stop filters, magnonic transistors and nanograting couplers. Here, spin‐wave excitations in artificial ferromagnetic quasicrystals created via aperiodic arrangement of nanoholes are studied experimentally. Their ten‐fold rotational symmetry results in multiplexed magnonic nanochannels, suggesting a width down to 50 nm inside a so‐called Conway worm. Key elements of design are emergent magnon motifs and the worm‐like features which are scale‐invariant and not present in the periodic metamaterials. By imaging wavefronts in quasicrystals, insight is gained into how the discovered features materialize as a dense wavelength division multiplexer. Abstract : Artificial ferromagnetic quasicrystals (AMQs) allow spin waves to form nanochannels, which incorporate peculiar sequences of bends, and thus the wavelength of the spin waves is different from nanochannel to nanochannel at a single input frequency. The results suggest that AMQs promise a new class of magnonic devices such as ultra‐compact and dense wavelength division multiplexers.