Simulations with an Ising-like Model for Dynamical Phase Transitions under Strong Excitation(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

概要

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We investigated theoretically the nonequilibrium steady state of a bistable molecular solid under continuous external excitation in terms of an Ising-like model. We performed Monte Carlo simulations and mean-field calculations, in both of which we found dynamical phase transitions with varying the intensity of external excitation Depending on the intermolecular coupling, the population of excited states grows with increasing the excitation intensity in different ways : a monotonic increase and saturation for weak coupling ; a sigmoidal increase for intermediate coupling, and the dynamical phase transition with a hysteresis for strong coupling In increasing the coupling further, the hysteresis region expands, and finally the excited state survives even when the excitation is turned off, corresponding to the ordinary photoinduced phase transition in equilibrium. These results are consistent with experiments in spin-crossover complexes under photoexcitation, including temperature dependence.
社団法人日本物理学会の論文
2004-12-15