Exchange anisotropy (or exchange bias) originating from the magnetic interaction between a ferromagnetic (FM) and an antiferromagnetic (AFM) structure is a fundamental physical effect [1,2], and it is utilized in fabrication of several spintronic devices such as magnetoresistive devices, magnetic sensors, and reading heads in magnetic hard disks. The phenomenon which is essentially observed in magnetic nanoparticles and thin films, is manifested as a vertical or horizontal shift in the hysteresis loops plotted in a plane of magnetization versus magnetic field strength. The parameters such as temperature, magnetic interactions in substance, nanoparticle radius (as well as the film thickness), and structural defects are the fundamental physical factors that have a direct impact on this phenomenon.
Dependence of exchange anisotropy on the factors mentioned above (temperature, magnetic interactions in substance, etc.) inspired a great deal of theoretical studies in the literature [3,4,5,6,7]. However, it is quite a challenge to control the aforementioned phenomena in real magnetic systems, since the nature of magnetic interactions, defects, and similar factors cannot be controlled externally. On the contrary, amplitude and frequency of externally applied oscillating magnetic fields [8] can be easily adjusted. Hence, application of this kind of magnetic fields on the material promises a more practical and effective
way of controlling the exchange anisotropy and SP phenomena. As far as we know, there is not any theortical or experimental
approach deaing with dynamical aspects of the problem.
In this presentation, using Monte Carlo simulations, we will discuss our recent results [9] on the dynamic phase transition
properties of magnetic nanoparticles with ferromagnetic core coated by an antiferromagnetic shell structure. Effects of field amplitude and frequency on the thermal dependence of magnetizations, magnetization reversal mechanisms during hysteresis cycles, as well as on the exchange bias and coercive fields will be presented, and the feasibility of applying dynamic
magnetic fields on the particle will also be discussed for technological and biomedical purposes.
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[9] Y. Yuksel and U. Akinci, J. Phys.: Condens. Matter 28 (2016) 486003
