95-218 Emilio Cirillo, Enzo Olivieri

METASTABILITY AND NUCLEATION FOR THE BLUME-CAPEL MODEL. DIFFERENT MECHANISMS OF TRANSITION. (284K, Plaintex) May 12, 95

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Abstract. We study metastability and nucleation for the Blume-Capel model: a ferromagnetic nearest neighbour two-dimensional lattice system with spin variables taking values in $\{-1,0,+1\}$. We consider large but finite volume, small fixed magnetic field $h$ and chemical potential $\lambda$ in the limit of zero temperature; we analyze the first excursion from the metastable $-1$ configuration to the stable $+1$ configuration. We compute the asymptotic behaviour of the transition time and describe the typical tube of trajectories during the transition. We show that, unexpectedly, the mechanism of transition changes abruptly when the line $ h = 2 \lambda$ is crossed.

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