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Coherent Magnons with Giant Nonreciprocity at Nanoscale Wavelengths.
Gallardo, Rodolfo; Weigand, Markus; Schultheiss, Katrin; Kakay, Attila; Mattheis, Roland; Raabe, Jörg; Schütz, Gisela; Deac, Alina; Lindner, Jürgen; Wintz, Sebastian.
Afiliação
  • Gallardo R; Universidad Técnica Federico Santa María, 2390123 Valparaíso, Chile.
  • Weigand M; Helmholtz-Zentrum Berlin, 12489 Berlin, Germany.
  • Schultheiss K; Helmholtz-Zentrum Dresden-Rossendorf, Insitute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany.
  • Kakay A; Helmholtz-Zentrum Dresden-Rossendorf, Insitute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany.
  • Mattheis R; Leibniz Institut für Photonische Technologien, 07745 Jena, Germany.
  • Raabe J; Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
  • Schütz G; Max-Planck-Institut für Intelligente Systeme, 70569 Stuttgart, Germany.
  • Deac A; Helmholtz-Zentrum Dresden-Rossendorf, Dresden High Magnetic Field Laboratory, 01328 Dresden, Germany.
  • Lindner J; Helmholtz-Zentrum Dresden-Rossendorf, Insitute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany.
  • Wintz S; Helmholtz-Zentrum Berlin, 12489 Berlin, Germany.
ACS Nano ; 2024 Feb 05.
Article em En | MEDLINE | ID: mdl-38314709
ABSTRACT
Nonreciprocal wave propagation arises in systems with broken time-reversal symmetry and is key to the functionality of devices, such as isolators or circulators, in microwave, photonic, and acoustic applications. In magnetic systems, collective wave excitations known as magnon quasiparticles have so far yielded moderate nonreciprocities, mainly observed by means of incoherent thermal magnon spectra, while their occurrence as coherent spin waves (magnon ensembles with identical phase) is yet to be demonstrated. Here, we report the direct observation of strongly nonreciprocal propagating coherent spin waves in a patterned element of a ferromagnetic bilayer stack with antiparallel magnetic orientations. We use time-resolved scanning transmission X-ray microscopy (TR-STXM) to directly image the layer-collective dynamics of spin waves with wavelengths ranging from 5 µm down to 100 nm emergent at frequencies between 500 MHz and 5 GHz. The experimentally observed nonreciprocity factor of these counter-propagating waves is greater than 10 with respect to both group velocities and specific wavelengths. Our experimental findings are supported by the results from an analytic theory, and their peculiarities are further discussed in terms of caustic spin-wave focusing.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Revista: ACS Nano Ano de publicação: 2024 Tipo de documento: Article País de afiliação: Chile País de publicação: Estados Unidos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Revista: ACS Nano Ano de publicação: 2024 Tipo de documento: Article País de afiliação: Chile País de publicação: Estados Unidos