Phase Transition in Cylindrical Ising Nanowires and Nanotubes: Approximation of the Molecular Field Theory

Resumo

Within the approximation of the molecular field theory, the critical behavior of cylindrical Ising nanowires and nanotubes is studied. The model considered in this work consists of ferromagnetic spins S_c situated in the core of the system and ferromagnetic spins S_s situated on the surface wall; they are interconnected by the exchange coupling J₁. The transition temperature T_c for such systems has been calculated as a function of exchange interaction parameters. The influence of the surface exchange interaction and surface coupling on the magnetodynamic behavior of the system have been studied. Some characteristic properties obtained on the phase diagram are related to the ratio of characteristic physical parameters on the surface and core of the abovementioned nanostructures.