Appearance Of First-order Phase Transition Research Articles

Double-well optical lattices with atomic vibrations and mesoscopic disorder

Double-well optical lattice in an insulating state is considered. The influence of atomic vibrations and mesoscopic disorder on the properties of the lattice are studied. Vibrations lead to the renormalization of atomic interactions. The occurrence of mesoscopic disorder results in the appearance of first-order phase transitions between the states with different levels of atomic imbalance. The existence of a nonuniform external potential, such as trapping potential, essentially changes the lattice properties, suppressing the disorder fraction and rising the transition temperature.

Magnetic properties of ultrasmall iron oxide nanoclusters in a polymer matrix

The synthesis of iron oxide nanoclusters in the matrix of an interpolyelectrolyte complex based on poly(acrylic acid) and polyethylenimine is described. The effect of the method of cluster formation (by the oxidation or reduction of iron ions) on the magnetic properties of polymer nanocomposites was studied. The influence of the surface modification of iron oxide nanoclusters in a polymer matrix on the interaction of the nanoclusters with the matrix, the appearance of first-order phase transitions, and the disappearance of superparamagnetism were examined. Mossbauer spectroscopy and magnetization measurements were used for identifying first-order magnetic phase transitions or superparamagnetism.