Spin-crossover is a change between a high-spin state and a low-spin state for atoms like Fe or Co in specific environments. I shall review the nature of phase transition of the spin-crossover and magnetic transitions in materials consisting of spin-crossover atoms. In particular, I shall study the general structure of phase transitions between the high-temperature and low-temperature phases, focussing on the metastable high-temperature phase at low temperature.
Department of Physics, University of Tokyo, Japan