Dynamic origin of segment magnetization reversal in thin-film Penrose tilings

F. Montoncello, L. Giovannini, B. Farmer, L. De Long

Research output: Contribution to journalLetterpeer-review

15 Scopus citations

Abstract

We investigate the low-frequency spin wave dynamics involved in the magnetization reversal of a Penrose P2 tiling using the dynamical matrix method. This system consists of a two-dimensional, connected wire network of elongated thin-film segments, whose complete reversal occurs as a cascade of successive local segment reversals. Using soft mode theory, we interpret the reversal of an individual segment as a first order magnetic transition, in which magnetization curve of the system suffers a small discontinuity. Near this discontinuity a specific mode of the spin wave spectrum goes soft (i.e., its frequency goes to zero), triggering a local instability of the magnetization. We show that this mode is localized, and is at the origin of the local reversal. We discuss the correlation of the mode spatial profile with the “reversal mechanism”, which is the passage of a domain wall through the segment. This process differs from reversal in periodic square or honeycomb artificial spin ices, where a cascade of reversing segments (e.g., “Dirac string”) follows an extended (though irregular) path across the sample; here the spatial distribution of successive segment reversals is discontinuous, but strictly associated with the area where a soft mode is localized. The migration of the localization area across the P2 tiling (during reversal in decreasing applied fields) depends on changes in the internal effective field map. We discuss these results in the context of spin wave localization due to the unique topology of the P2 tiling.

Original languageEnglish
Pages (from-to)158-163
Number of pages6
JournalJournal of Magnetism and Magnetic Materials
Volume423
DOIs
StatePublished - Feb 1 2017

Bibliographical note

Funding Information:
Research at University of Kentucky was supported by U.S. NSF Grant DMR-1506979 .

Publisher Copyright:
© 2016 Elsevier B.V.

Keywords

  • Artificial quasi-crystals
  • Frustrated systems
  • Magnonic crystals
  • Soft modes
  • Spin waves

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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