Omnidirectional flat bands in chiral magnonic crystals

J. Flores-Farías*, R. A. Gallardo, F. Brevis, A. Roldán-Molina, David Cortés-Ortuño, P. Landeros

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The magnonic band structure of two-dimensional chiral magnonic crystals is theoretically investigated. The proposed metamaterial involves a three-dimensional architecture, where a thin ferromagnetic layer is in contact with a two-dimensional periodic array of heavy-metal square islands. When these two materials are in contact, an anti-symmetric exchange coupling known as the Dzyaloshinskii–Moriya interaction (DMI) arises, which generates nonreciprocal spin waves and chiral magnetic order. The Landau–Lifshitz equation and the plane-wave method are employed to study the dynamic magnetic behavior. A systematic variation of geometric parameters, the DMI constant, and the filling fraction allows the examination of spin-wave propagation features, such as the spatial profiles of the dynamic magnetization, the isofrequency contours, and group velocities. In this study, it is found that omnidirectional flat magnonic bands are induced by a sufficiently strong Dzyaloshinskii–Moriya interaction underneath the heavy-metal islands, where the spin excitations are active. The theoretical results were substantiated by micromagnetic simulations. These findings are relevant for envisioning applications associated with spin-wave-based logic devices, where the nonreciprocity and channeling of the spin waves are of fundamental and practical scientific interest.
Original languageEnglish
Article number17831
Pages (from-to)1-11
Number of pages11
JournalScientific Reports
Volume12
Issue number1
DOIs
Publication statusPublished - Dec 2022

Keywords

  • magnonics
  • micromagnetics
  • magnons
  • spin waves
  • flat bands
  • Dzyaloshinskii-Moriya interactions

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