A theory of magnetization reversal in nanowires

Research output: Contribution to journalConference article

2 Scopus citations

Abstract

Magnetization reversal in a ferromagnetic nanowire which is much narrower than the exchange length is believed to be accomplished through the thermally activated growth of a spatially localized nucleus, which initially occupies a small fraction of the total volume. To date, the most detailed theoretical treatments of reversal as a field-induced but noise-activated process have focused on the case of a very long ferromagnetic nanowire, i.e., a highly elongated cylindrical particle, and have yielded a reversal rate per unit length, due to an underlying assumption that the nucleus may form anywhere along the wire. But in a bounded-length (though long) cylindrical particle with flat ends, it is energetically favored for nucleation to begin at either end. We indicate how to compute analytically the energy of the critical nucleus associated with either end, i.e., the activation barrier to magnetization reversal, which governs the reversal rate in the low-temperature (Kramers) limit. Our treatment employs elliptic functions, and is partly analytic rather than numerical. We also comment on the Kramers prefactor, which for this reversal pathway does not scale linearly as the particle length increases, and tends to a constant in the low-temperature limit.

Original languageEnglish (US)
Pages (from-to)48-57
Number of pages10
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume5471
DOIs
StatePublished - Sep 14 2004
EventNoise in Complex Systems and Stochastic Dynamics II - Maspalomas
Duration: May 26 2004May 28 2004

Keywords

  • Activation barrier
  • Ferromagnetic cylinder
  • Ferromagnetic nanowire
  • Kramers prefactor
  • Kramers theory
  • Landau-Lifshitz-Gilbert equation
  • Magnetization reversal
  • Néel-Brown theory
  • Weak spatiotemporal noise

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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