Size-induced depression of first-order transition lines and entropy-jump   in extremely-layered nanocrystalline vortex matter
  We detect the persistence of the solidification and order-disorder first-order transition lines in the phase diagram of nanocrystalline Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$ vortex matter down to a system size of less than hundred vortices. The temperature-location of the vortex solidification transition line is not altered by decreasing the sample size although there is a depletion of the entropy-jump at the transition with respect to macroscopic vortex matter. The solid order-disorder phase transition field moves upward on decreasing the system size due to the increase of the surface-to-volume ratio of vortices entailing a decrease on the average vortex binding energy. 
M.I. Dolz, Y. Fasano, N. R. Cejas Bolecek, H. Pastoriza, V. Mosser, M.   Li, M. Konczykowski
cond-mat.supr-con