Enhanced Cooperative Interactions at the Nanoscale in Spin-Crossover Materials with a First-Order Phase Transition

authors	Felix, G; Nicolazzi, W; Salmon, L; Molnar, G; Perrier, M; Maurin, G; Larionova, J; Long, J; Guari, Y; Bousseksou, A
journal	PHYSICAL REVIEW LETTERS
keywords	ISING-LIKE MODEL; THERMAL HYSTERESIS; ROOM-TEMPERATURE; SIZE DEPENDENCE; NANOPARTICLES; NANOCRYSTALS; BISTABILITY; COMPLEXES
abstract	We analyzed the size effect on a first-order spin transition governed by elastic interactions. This study was performed in the framework of a nonextensive thermodynamic core-shell model. When decreasing the particle size, differences in surface energies between the two phases lead to the shrinking of the thermal hysteresis width, the lowering of the transition temperature, and the increase of residual fractions at low temperature, in good agreement with recent experimental observations on spin transition nano-materials. On the other hand, a modification of the particle-matrix interface may allow for the existence of the hysteresis loop even at very low sizes. In addition, an unexpected reopening of the hysteresis, when the size decreases, is also possible due to the hardening of the nanoparticles at very small sizes, which we deduced from the size dependence of the Debye temperature of a series of coordination nanoparticles.
publisher	AMER PHYSICAL SOC
issn	0031-9007
year published	2013
volume	110
issue	23
digital object identifier (doi)	10.1103/PhysRevLett.110.235701
web of science category	Physics, Multidisciplinary
subject category	Physics
unique article identifier	WOS:000320115000015