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1. #Exchange bias effect of magnetic core shell nanoparticles update
2. #Exchange bias effect of magnetic core shell nanoparticles free

#Exchange bias effect of magnetic core shell nanoparticles free

While free uncompensated AFM spins increase the coercivity of the system, pinned uncompensated AFM spins results in an induced unidirectional anisotropy, i.e., the exchange bias. To start with an intuitive model, it can be assumed that uncompensated interface spins of the AFM (i.e., the AFM spins whose summation vectors are not zero) couple to the FM. Naturally, with new experimental findings, new models are necessary, sometimes only valid for very special cases, sometimes explaining a broad range of phenomena at least qualitatively. This is why after the first intuitive models, several other emerged, aiming at explaining as many experimentally observed effects as possible in a physically reasonable way. Modeling the Exchange BiasĮxplaining all the aforementioned phenomena qualitatively and quantitatively by a model is obviously difficult, especially as different effects are found in different material systems or even in identical material systems, prepared in different ways. To avoid the additional impact of an in-plane component of the shape anisotropy in nanostructured or nanoparticle systems, we concentrate in this review on thin film samples, where the shape anisotropy often results in the magnetic moments being oriented in-plane.

#Exchange bias effect of magnetic core shell nanoparticles update

Here, we give an update of recent experimental and theoretical research in the area of exchange bias. Still, at the same time, new models are being developed to understand the exchange bias effect, which is already intensively used in magnetic data storage, qualitatively and quantitatively for all these different material combinations and structures. While first studies concentrated on relatively simple FM/AFM combinations, such as the aforementioned Co/CoO, Fe/FeF 2, or Fe/MnF 2, which already exhibited quite interesting effects for the different materials, nowadays more complicated materials are under investigations, such as Fe/LaAlO 3 or Pr 0.67Sr 0.33MnO 3/SrTiO 3, and more sophisticated structures, such as nanostructures or multi-layer sandwiches. However, other correlated phenomena, such as a vertical shift of the loop and an often occurring asymmetry of the hysteresis loop, cannot be explained by this most simple model. In a naïve concept, this process freezes the AFM spins, in this way adding an “internal” magnetic field to the external one which leads to a horizontal shift of the FM hysteresis loop. Typically, it occurs when a ferromagnet (FM) and an antiferromagnet (AFM) are in contact, and the system is cooled from high temperatures through the Néel temperature (the magnetic ordering temperature) of the AFM in an external magnetic field. After its discovery in 1956, using Co/CoO core–shell particles, the exchange bias (EB) effect has been investigated in detail by many research groups.