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Effect of exchange interaction on superparamagnetic relaxation

H. Kachkachi
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Abstract

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 $j\equiv J/K = j_c\equiv 1-h^2$, where $h\equiv H/2K$, which separates two regimes corresponding to a two-stage and one-stage switching. For $j\gg j_c$ the Néel-Brown result for the one-spin problem is recovered.

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BibTeXRIS

H. Kachkachi. 2003-05-19. Effect of exchange interaction on superparamagnetic relaxation. https://doi.org/10.1209/epl%2Fi2003-00423-y

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