The Studies Of Exchange Bias And Coercivity For Ferromagnetic/Antiferromagnetic Films

In this thesis,we perform Monte Carlo method to study the effects of the interface magnetic dilution, the cooling field,the thickness of FM and AFM on the exchange bias and coercivity for ferromagnetic/antiferromagnetic films, The main contents of this paper are arranged as follows:1、The essential conception,sort and physical characters of nanostructured magnetic materials are introduced in brief. Moreover,we mostly present the basal theory and the Monte Carlo method are given:2、Based on the Monte Carlo simulations, we investigate the effects of the interface magnetic dilution, the cooling field,the thickness of FM and AFM on the exchange bias and coercivity for ferromagnetic/antiferromagnetic films, respectively. From the simulated results, we can find that:(1) The interface magnetic dilution X1has important influence on the exchange bias and coercivity, As the interface is diluted with some magnetic atoms, He is close to zero and the coercivity He enhancement appears.It is aslo observed that the peak of He occurs in the He-X1curves.(2) The exchange bias and coercivity relate with the cooling field,the appearance of the positive exchange bias is strongly dependent on the interface exchange coupling between FM and AFM atoms.(3) The exchange bias and coercivity is closely related to the dilution of the nonmagnetic atoms in the AFM layer. The simulated results is similar to the conclusion in the (1).(4) The values of He versus JAB has no correlation with the sign of JAB.However, the values of He versus JAB relates with the sign of JAB.(5)The values of He versus the thickness of the FM layes and AFM layers have correlation with the dilution of the nonmagnetic atoms in the AFM layer. In the range of certain FM layers, He is inversely protortional to the thickness of the FM layes.(6) the amplitude and frequency of sweeped magnetic field influence significantly the exchange bias and coercivity.