Enhanciement of exchange bias with diluted antiferromagnets in FM/AFM bilayers

Abstract

Based on Monte Carlo method, the characteristic of exchange bias is discussed in diluted antiferromagnets in FM/AFM bilayers by changing the dilute concentration. The simulation results show that the exchange bias in FM/AFM bilayers can be enhanced significantly by introducing nonmagnetic atoms into the AFM layers. And there is a maximum in the diagram of exchange bias as a function of the dilute concentration, i.e., the exchange bias at first increases then decreases with increasing concentration of dilution at the same temperature. Besides, the maximum of the exchange bias occurs at lower concentration for higher temperature. These are consistent with the results of Phys. Rev. Lett. 96 117204 (2006). The cause of these results is that the spin distribution and the magnetic domain structure change greatly when varying dilute concentration. The exchange bias is maximal when the positive and the negative magnetic domains form a connected network. In addition, at the same concentration of dilution, by comparing the results of the random and regular dilution, we find that the exchange bias are more strongly increased by regular dilution than by random dilution for the FM/AFM bilayers, which shows further that the characteristic of exchange bias in FM/AFM bilayers depends on the interface spin-microstructure.

The Influnence of the Amplitude and Frequency of Sweeped Magnetic Field on the Exchange Bias and Coercivity for Ferromagnetic / Antiferromagnetic Films: Monte Carlo Simulation

“…Since the novel magnetic properties of EB are conducive to improve magnetic sensor and recording technologies effectively, the studys on the EB have recently attracted considerable interest in experiment and theory. For example, many authors have studied a variety of effects of the exchange bias, such as temperature [6,7], cooling field [8], interface exchange coupling constant [9], thickness [10,11], dopants and defects [12] as well as the antiferromagnetic dilution [13,14].Recently, the effect of interface magnetic dilution on exchange bias is studied with extensive Monte Carlo simulations for a model system consisting of a ferromagnetic layer exchange coupled to a diluted antiferromagnet [15]. It is found that the magnetic dilution and bond distribution of the ferromagnetic interface layer can lead to an increase in the bias field magnitude.…”

Unified nonequilibrium dynamical theory for exchange bias and training effects

“…Moreover, under the reversal of FM domains, the uncompensated grains or domains will be irreversibly reorganized [15−19] and thus cause the training effect. Although different models are adopted by some simulations [20,21] and theoretical investigation, [22−26] actual nonequilibrium dynamical properties of the magnetization are still waiting to be elucidated. It is highly desirable and needed to systematically investigate the two effects in a unified theory.…”

Modelling of spreading process: effect from hydrogen bonds

“…In this paper, molecular dynamics (MD) simulation [14] based on a coarse-grained bead-spring model is performed to examine the spreading process on solid substrates. Particularly, the hydrogen bonds among lubricant molecules and the hydrogen bonds between lubricant molecules and solid substrates are studied in detail.…”