Issue |
Europhys. Lett.
Volume 62, Number 5, June 2003
|
|
---|---|---|
Page(s) | 650 - 656 | |
Section | General | |
DOI | https://doi.org/10.1209/epl/i2003-00423-y | |
Published online | 01 May 2003 |
Effect of exchange interaction on superparamagnetic relaxation
Laboratoire de Magnétisme et d'Optique, Université de Versailles St. Quentin 45 av. des Etats-Unis, 78035 Versailles Cedex, France
Corresponding author: kachkach@physique.uvsq.fr
Received:
21
January
2003
Accepted:
2
April
2003
We use Langer's approach to calculate the reaction rate of a system of two (classical) spins interacting via the exchange coupling J in a magnetic field H, with uniaxial anisotropy of constant K. We find a particular value of the exchange coupling, that is , where , which separates two regimes corresponding to a two-stage and one-stage switching. For the Néel-Brown result for the one-spin problem is recovered.
PACS: 05.40.-a – Fluctuation phenomena, random processes, noise, and Brownian motion / 75.50.Tt – Fine-particle systems; nanocrystalline materials
© EDP Sciences, 2003
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