Magnetization field-dependences and the “exchange bias” in ferro/antiferromagnetic systems. I. Model of a bilayer ferromagnetic

2012

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The influence of magnetic anisotropy of ferromagnetic film on the phenomenon of exchange bias is studied. Hysteresis behavior in the two-spin model of a ferro/antiferromagnet (FM/AFM) bilayer with exchange bias has been investigated in detail. In this model a half-space of AFM with fixed magnetic configuration contacts with a two-layer FM film. Twelve different types of magnetization curves M(H) (both with and without hysteresis) have been found. Some of the M(H) curves demonstrate unusual features, such as plateaus and inclined segments. The hysteresis loop becomes asymmetric if the surface anisotropy is taken into account.

Section: Introductionmentioning

confidence: 99%

Influence of magnetic anisotropy on hysteresis behavior in the two-spin model of a ferro/antiferromagnet bilayer with exchange bias

Grechnev

2012

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“…13, two hysteresis loops do not arise within the long-wavelength model. Below we show that for a fixed value of the external field, only two different solutions of the system (3) …”

Section: Model Formulationmentioning

confidence: 92%

“…For a "thin" film with L ( l 1 (which is satisfied for J 0 ( J), the bifurcation field is H þ =J % Àa 2 =Ll 1 À ða=l 0 Þ 2 ¼ ÀðJ 0 =JÞða=LÞ À b=J: (13) In this case, the main "exchange" shift is now dependent on the interlayer interaction and, if the interaction is small, can be of the order of the shift due to the anisotropy and, for J 0 < JaL=l 2 0 , even smaller than it. (In the limit J 0 !…”

Section: Model Formulationmentioning

confidence: 99%

Effect of the exchange bias on the magnetization hysteresis of a ferromagnetic film in contact with an antiferromagnet

Grechnev

2013

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The transformation of the hysteretic field dependence of the magnetization of a ferromagnetic thin layer in contact with a magnetically hard antiferromagnet is considered. It is shown that this interaction leads to a shift of the hysteresis loop from the configuration symmetric with respect to magnetic field (exchange bias). Furthermore, upon increasing the magnitude of the exchange interaction, within a narrow range of the magnitudes, there occurs a qualitative change in the hysteresis loop shape and its subsequent disappearance; hence the field dependence of the magnetization becomes monotonous and single-valued.

“…7 and 8. The magnetic anisotropy is not included in boundary conditions (5) and (6), but only in Eqs.…”

Section: Inhomogeneous States Of Anisotropic Ferromagnetic Filmmentioning

confidence: 99%

“…This model provides a quality description of a shift in the field dependence hysteresis loop, in the case of an ideal interface between the FM/ layered AFM, with the layers parallel to the interface itself. 2,[4][5][6][7][8] However, the EB is observed even in the case of a compensated boundary, and can be explained by non-ideality (roughness) of the interface. The latest experiments have shown [9][10][11] that aside from EB, the field dependence of magnetization can have additional, and fairly complex properties: the appearance of a "horizontal plateau" with constant magnetization in a range of fields, the differing of the slope of the M ¼ M(H) dependence, in accordance to different field values, and the hysteresis loop itself "splitting" into two symmetrical or asymmetrical loops.…”

Section: Introductionmentioning

confidence: 99%

Properties of ferromagnetic film hysteresis, on the surface of a hard-magnetic antiferromagnet, with a domain structure

2014

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This is a theoretical investigation of the exchange bias phenomenon, and the properties of a thin magnetic film's magnetization hysteresis loop, on the rough surface of a hard-magnetic antiferromagnet. An interface model with a periodic structure of atomic steps is presented. These atomic steps are associated with a spatially inhomogeneous distribution of the ferromagnetic film magnetization, akin to a system of domain walls. This structure leads to a complicated external field dependence of magnetization: the hysteresis curve can assume an asymmetrical shape and "fall apart" into two hysteresis loops, divided by a "horizontal plateau," or an area with constant fieldindependent magnetization. Such field dependence behavior has been recently observed experimentally in different ferro/antiferromagnet systems. The field dependence of magnetization has been obtained analytically using the long-wave approximation for various characteristics of ferromagnetic film (its thickness, values of exchange interaction, and magnetic anisotropy), and the interface (the period of the inhomogeneous structure, and exchange interaction through the interface). The analytical results are confirmed by numerical calculations for the corresponding discrete model with a more complex interface structure. V