J. Phys. IV France 114 (2004) 637
Two-step photo-induced phase transitions in a two-sublattice modelY. Otsuka1, 1 and K. Yonemitsu1, 2, 1
1 Department of Theoretical Studies, Institute for Molecular Science, Okazaki 444-8585, Japan
2 Graduate University for Advanced Studies, Okazaki 444-8585, Japan
As an effective model for the two-step spin transition, we study a two-sublattice spin model that takes into account intra-site antiferromagnetic and inter-site ferromagnetic couplings. Due to the competition between these couplings, the temperature dependence of the high spin fraction shows a two-step transition. We perform Monte Carlo (MC) simulations including a photoexcitation term. The MC dynamics of the high spin fraction shows non-linear characteristics such as step-like changes, threshold-like behavior, and phase separation. Key words. spin-crossover complex, photo-induced phase transition, domain formation.
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