Molecular dynamics simulation of the melting of uranium dioxide nanocrystals

The melting of vacuum-isolated uranium dioxide (UO₂) nanocrystals is studied by molecular dynamics simulation using the approximation of pair potentials and point ions. The size dependences of the melting temperature, the heat of melting, and the density jump of cubic crystals up to 1000 nm³ in size are measured for the ten most relevant sets of pair potentials. The linear and parabolic extrapolations of these dependences to macroscopic sizes are considered, and the parabolic extrapolation is found to be better for analyzing data on the melting temperature and heat.     

Magnetiostatic interactions in some bubble-domain propagation circuits

Cylindrical magnetic domain (CMD) propagation actually comes to the generation of magnetostatic traps (MST) which successively "capture" the domains on their way along the propagation path. There are three types of MST which correspond to three types of magnetostatic interactions between a domain magnetization and "active" elements of propagation circuits. An interaction of CMD magnetization with ferromagnetic overlay (the third type of an interaction) can generate MST with the maximum depth of approximately 16 Oe. NIST depth in practical propagation circuits is bound to be 6-10 Oe. The data rate upper limit for the techniques using the interaction of CMD and ferromagnetic overlay is determined by the minimum time interval necessary for domain capture by MST and for orthoferrites, which is approximately 1 Mbit/s. The rare-earth orthoferrite single crystals synthesized by the floating zone technique were used throughout the experiments.