Monte Carlo models of the magnetization reversal in thin films with strong perpendicular anisotropy

Abstract

A variety of different models and Monte Carlo algorithms are used to study the magnetization reversal in thin films with perpendicular magnetization. The thin film is represented by a two-dimensional micromagnetic grid or array of classical Ising spins, with long-range dipolar and a short-range effective exchange interaction arising from the contribution of the domain-wall energy. The selection of an appropriate model requires some knowledge of the defects that may be present in the film and their mechanism of interaction with the domain boundary. Magnetic viscosity and equilibrium domain structures are simulated using the Metropolis algorithm with or without an additional energy barrier. Other algorithms are useful when the process of nucleation and growth of magnetic domains involves a wide distribution of relaxation times. We study the relationship between the methods and discuss their relative merits and range of application.

Magnetic field scaling of relaxation curves in small particle systems

“…Notice that these two prefactors are often neglected in theoretical studies of the dependence of the blocking temperature with the field 1 and Monte Carlo simulations. 35,39 This is due to the fact that, usually, the possibility of jumping between minima by any of the two channels is not considered. However, at small nonzero fields ( տ0), and for particles oriented at 0, they can be equally relevant.…”

Phase diagram of three contrasting magnetization reversal phases in uniaxial ferromagnetic thin films

“…4,7 Micromagnetic calculations have indeed demonstrated the contrasting change of simulated domain evolution patterns with respect to the magnetic properties. [7][8][9][10][11][12][13] Kirby et al 8 first presented simulated results of contrasting behavior from wall motion to nucleation-dominant magnetization reversal with respective to the domain wall energy, which could explain the experimental observations in Dy/Fe multilayers well. Lyberatos et al 9 developed a more generalized micromagnetic description of magnetization reversal, which predicted three contrasting behaviors among the wallmotion, nucleation, and dendritic-growth processes depending on the magnetic properties of samples.…”

“…Several equivalent models have been reported to explain the magnetization reversal behavior observed in a number of different sample systems, 7,10 taking into consideration the local magnetic variation. 11,12 Quite recently, Lyberatos 13 summarized the various micromagnetic algorithms and their relevancy for each physical situation.…”

Monte Carlo simulations of dynamic phase transitions in ultrathin Blume–Capel films

“…In addition to the fundamental purpose, thin film materials have great importance in technological applications. For instance, ultrathin Au/Co/Au magnetic films, CoPt-alloy films, CoNi/Pt and Tb/Fe multilayers are considered as potential candidates of raw materials in ultrahigh-density magneto-optic recording devices [9].…”