Study On The Magnetism Of A Mixed Magnetic Film By Micromagnetism And Monte Carlo Simulation

The magnetoresistance and exchange bias arising from the magnetic multilayer and granular films have great applicable importance in the field of the magnetic memorization and the magnetic sensor. The exchange bias found in the ferromagnetic and antiferromagnetic mixed magnetic films even have aroused considerable interest in recent years.Here, the magnetic properties of ferromagnetic and antiferromagnetic mixed magnetic films are simulated by a micromagnetism method based on the principle of energy minimum and Monte Carlo technology. A step effect of M - H magnetization curve is evidently observed and and the result calculated by a simple Ising model reveals that the step-like effect may be produced in the antiferromagnetic coupling system with small number of spins. The hysteresis loops, spin configurations, and the influences of exchange constant, uniaxial anisotropy constant, dipolar interaction constant and diluted ratio of ferromagnetic atom on the coercivity at the ground states are studied systematically for the studied systems. These simulated results explain the experimental facts in the granular films with antiferromagnetic coupling well. At the same time, the temperature dependence of the coercivity is calculated. We find that the T dependence of the value of HC for the films with different magnitude of Xcan be described by the law of T1 well. but the value of a has a complex variety with the change of X. Finally, we study the size effect of hysteresis in the mixed magnetic films. It is found that the step effect and the coercivity are influenced by the size of the mixed magnetic films greatly.