Langevin simulation of thermally activated magnetization reversal in nanoscale pillars

Gregory Brown, M. A. Novotny, and Per Arne Rikvold
Phys. Rev. B 64, 134422 – Published 13 September 2001
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Abstract

Numerical solutions of the Landau-Lifshitz-Gilbert micromagnetic model incorporating thermal fluctuations and dipole-dipole interactions (calculated by the fast multipole method) are presented for systems composed of nanoscale iron pillars of dimension 9nm×9nm×150nm. Hysteresis loops generated under sinusoidally varying fields are obtained, while the coercive field is estimated to be 1979±14Oe using linear field sweeps at T=0K. Thermal effects are essential to the relaxation of magnetization trapped in a metastable orientation, such as happens after a rapid reversal of an external magnetic field less than the coercive value. The distribution of switching times is compared to a simple analytic theory that describes reversal with nucleation at the ends of the nanomagnets. Results are also presented for arrays of nanomagnets oriented perpendicular to a flat substrate. Even at a separation of 300 nm, where the field from neighboring pillars is only 1Oe, the interactions have a significant effect on the switching of the magnets.

  • Received 31 January 2001

DOI:https://doi.org/10.1103/PhysRevB.64.134422

©2001 American Physical Society

Authors & Affiliations

Gregory Brown1, M. A. Novotny1, and Per Arne Rikvold1,2

  • 1School of Computational Science and Information Technology, Florida State University, Tallahassee, Florida 32306-4120
  • 2Center for Materials Research and Technology and Department of Physics, Florida State University, Tallahassee, Florida 32306-4350

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Vol. 64, Iss. 13 — 1 October 2001

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