Investigation of the exchange mechanism in NiFe-TbCo bilayers

Cain, William; Kryder, M.H.

doi:10.1063/1.346107

Cited by 118 publications

(57 citation statements)

References 8 publications

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“…Exchange bias is expected in metal-rare earth (TM-RE) systems at temperatures where the RE exists in the antiferromagnetic (AF) phase [1][2][3][4]. RE elements such as Gd, Sm, Dy and Tb have been used regularly to form ferrimagnetic alloys with ferromagnetic (FM) elements, which become coupled to FM alloys to show a sizable exchange bias field H eb [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Exchange-bias-like coupling in a Cu-diluted-Fe/Tb multilayer

et al. 2015

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Transition metal-rare earth (TM-RE) Fe/Tb-multilayer systems have been known to show exchange-bias-like shifts in the form of double hysteresis loop (DHL) along and opposite to the field cooling axis. Planar domain walls (DW), with opposite handedness at the interfaces, are held responsible for such DHL. Here, we report on the formation of nanoparticulated Fe layers in the Cu-matrix within a Fe-Cu/Tb multilayer and their eventual low temperature characteristics. AC susceptibility measurements indicate that these diluted magnetic clusters have a superspin-glass type of freezing behavior. Eventually, this Fe-cluster/Tb interlayer interaction, which is conjectured to be mediated by the pinned moments within the individual clusters, has helped in increasing the exchange bias field in the system to a high value of ≈1.3 kOe which gradually vanishes around 50 K. Polarized neutron reflectivity confirms a very strong antiferromagnetic (AF) coupling between the individual layers. The magnitude of the magnetic moment of each of the individual Tb or Fe-Cu layer remains similar but due to the strong AF-coupling at the interfaces, the entire ferrimagnetic Fe-Cu/Tb entity flips its direction at a compensation field of around 3.7 kOe. This study shows that magnetic dilution can be an effective way to manipulate the possible domain walls or the clusters in TM and thereby the exchange bias in TM-RE systems.

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Section: Introductionmentioning

confidence: 99%

Exchange-bias-like coupling in a Cu-diluted-Fe/Tb multilayer

et al. 2015

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“…Since then various antiferromagnets (AF), which are exchange coupled to ferromagnets (F), have shown H EB [2][3][4][5][6]. There are well written reviews on the subject listing possible configurations [2,[7][8][9] and there are several theories [10][11][12][13][14] which give reasonable values in agreement with experiment.…”

mentioning

confidence: 88%

Thickness dependence of oscillatory exchange bias

Demirtas

Köymen

2005

Journal of Magnetism and Magnetic Materials

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“…Besides the classical system of AF/FM interfaces, EB and related effects have been observed also in other types of samples, e.g. involving ferrimagnets (FI): AF/FI 13 , FI/FM [14][15][16] and lately also in FI/FI 17 with a compensated spin structures at the interface. Transition Metal-Rare Earth (TM-RE) alloys, in particular, are nowadays suggested to used as FI materials in magnetic hybrid structures exhibiting strong EB effects 18 .…”

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Observation of an atomic exchange bias effect in DyCo<inf>4</inf> film

Chen

Dieter

Radu

2015

2015 IEEE Magnetics Conference (INTERMAG)

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The fundamental important and technologically widely employed exchange bias effect occurs in general in bilayers of magnetic thin films consisting of antiferromagnetic and ferromagnetic layers where the hard magnetization behavior of an antiferromagnetic thin film causes a shift in the magnetization curve of a soft ferromagnetic film. The minimization of the single magnetic grain size to increase the storage density and the subsequent demand for magnetic materials with very high magnetic anisotropy requires a system with high H EB . Here we report an extremely high H EB of 4 Tesla observed in a single amorphous DyCo 4 film close to room temperature. The origin of the exchange bias can be associated with the variation of the magnetic behavior from the surface towards the bulk part of the film revealed by X-ray absorption spectroscopy and X-ray magnetic circular dichroism techniques utilizing the bulk sensitive transmission and the surface sensitive total electron yield modes. The competition between the atomic exchange coupling in the single film and the Zeeman interaction lead to an intrinsic exchanged coupled system and the so far highest exchange bias effect H EB = 4 Tesla reported in a single film, which is accommodated by a partial domain wall formation.Exchange bias effect (EB) was discovered in 1956 by Meiklejohn and Bean when studying Co particles embedded in their native antiferromagnetic oxide 1 . It is generally considered to form from an uncompensated spin configuration at the ferromagnetic/antiferromagnetic (FM/AF) interface 2,3 , as it is the case in small particles, inhomogeneous materials, FM films on AF single crystals and FM on AF thin films 4 with frozen and rotatable spins at their interfaces [5][6][7][8][9] . Phenomenologically, the EB effect in FM/AF systems displays a shift of the hysteresis by an EB field H EB that is achieved by a magnetic field cooling procedure down to the Néel temperature T N of the AF. The experimentally observed value of the H EB in FM/AF systems, however, is in general several orders of magnitude below the theoretical prediction for a perfect EB system 10 . This discrepancy resulted in a heavy debate and the development of sophisticated models for the explanation of the origin of the EB effect and its drastic reduction of the EB effect in real EB systems 4,11,12 . Besides the classical system of AF/FM interfaces, EB and related effects have been observed also in other types of samples, e.g. involving ferrimagnets (FI): AF/FI 13 , FI/FM 14-16 and lately also in FI/FI 17 with a compensated spin structures at the interface. Transition Metal-Rare Earth (TM-RE) alloys, in particular, are nowadays suggested to used as FI materials in magnetic hybrid structures exhibiting strong EB effects 18 . Besides an interfacial exchange between two chemically and magnetically different compositions, a physically induced magnetic phase deviation from the bulk to the surface may also results into an exchange bias effect although there is no obvious chemical interface in the sample. The...

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Investigation of the exchange mechanism in NiFe-TbCo bilayers

Cited by 118 publications

References 8 publications

Exchange-bias-like coupling in a Cu-diluted-Fe/Tb multilayer

Exchange-bias-like coupling in a Cu-diluted-Fe/Tb multilayer

Thickness dependence of oscillatory exchange bias

Observation of an atomic exchange bias effect in DyCo<inf>4</inf> film

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