Pi pulses in a ferromagnet: Simulations for yttrium iron garnet

Jinho Lim*, Zhaohui Zhang, Anupam Garg, John B. Ketterson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Using a many spin micromagnetic simulation tool that directly integrates the Landau-Lifshitz equation, we demonstrate that by applying an r.f. pulse, generally referred to as a Pi pulse, it is possible to near-perfectly reverse the direction of the magnetization in a ferromagnet, provided that the sample is sufficiently small and the angular dependence of the precession frequency is continuously matched using an appropriately “chirped” r.f. pulse of the proper length. Simulations are carried out for “prolate” uniaxially symmetric cylindrical samples in the presence of dipole and exchange interactions. Such reversals can be performed in the presence of a static external magnetic field or, importantly, at zero field under the sample's own internal demagnetization field. However, the ability to perform near-perfect Pi or two-Pi rotations is lost for samples above certain dimensions for which additional internal degrees of freedom are excited, particularly at higher static fields. In such larger samples the magnetization may still be reversed by utilizing damping, provided it can be rotated past a critical angle.

Original languageEnglish (US)
Article number167787
JournalJournal of Magnetism and Magnetic Materials
Volume527
DOIs
StatePublished - Jun 1 2021

Keywords

  • Chirped microwave
  • Micromagnetic simulation
  • Microwave assisted switching
  • Nonlinear FMR
  • Pi pulses in a ferromagnet
  • Suhl instability

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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