ABSTRACT
Based on Glauber-type stochastic dynamics intertwined with mean field theory, we have investigated a graphene nanoisland's out-of-equilibrium magnetic and thermomagnetic behaviors with a mixed ferrimagnetic spin (1/2, 1) configuration in the presence of an oscillating magnetic field. The influence of the oscillating external magnetic field, single-ion anisotropy and temperature on the dynamic magnetic properties (dynamic phase transitions, hysteresis loop areas, correlations, and phase diagrams) of the system is studied in detail. The results illustrate that single ion anisotropy and the magnetic field play important roles in the system's dynamic order parameters, phase transitions and phase diagrams. Dynamic phase diagrams display some dynamic special points such as dynamic tricritical points, quadruple points and some sort of reentrant phenomena, which strongly depend on interaction parameters. Our predicted results may provide a reference for future experimental and theoretical studies of the nanostructures.
ABSTRACT
The stationary states of the kinetic Ising model described by the Glauber stochastic dynamics subject to a time-dependent oscillating external magnetic field was analyzed in detail on the Bethe lattice in terms of the recursion relation. The dynamic order parameter, the hysteresis loop area, and the dynamic correlation are calculated. It was found that the magnetization oscillates around nonzero values at low temperatures for the ferromagnetic phase while it only oscillates around zero values at high temperatures for the paramagnetic phase for appropriate values of the oscillating external magnetic field. The dynamic phase diagrams of the system are obtained for the given coordination numbers q=4 and 6. In addition to the second- and first-order phase transitions, the dynamical tricritical points are also observed.
