Transport anisotropy in hetero-amorphous (CoFeB)–SiO2 thin films

Johnsson, P.; Aoqui, Shin-ichi; Grishin, Alexander M.; Munakata, Mitsuru

doi:10.1063/1.1558238

Cited by 17 publications

(19 citation statements)

References 8 publications

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“…The measured magnetoresistance curves contained the contribution from only tunneling magnetoresistance and did not contain the contribution from the anisotropic magnetoresistance. Since latter contribution in such films appears for x > x c only [25], this result proves above assertion. For the above sample, the experimental data for magnetization in the film plane along easy direction (curve 1) at room temperature are presented on the inset to Fig.…”

Section: Results Of Modelingsupporting

confidence: 82%

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The influence of intergranular interaction on the magnetization of the ensemble of oriented Stoner–Wohlfarth nanoparticles

Timopheev

Ryabchenko

Каліта

et al. 2009

Journal of Applied Physics

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We consider the influence of interparticle interaction on the magnetization reversal in the oriented Stoner-Wohlfarth nanoparticles ensemble. To do so, we solve a kinetic equation for the relaxation of the overall ensemble magnetization to its equilibrium value in some effective mean field. Latter field consists of external magnetic field and interaction mean field proportional to the instantaneous value of above magnetization. We show that the interparticle interaction influences the temperature dependence of a coercive field. This influence manifests itself in the noticeable coercivity at T > T b (T b is so-called blocking temperature). The above interaction can also lead to a formation of the "superferromagnetic" state with correlated directions of particle magnetic moments at T > T b .This state possesses coercivity if the overall magnetization has a component directed along the easy axis of each particle. We have shown that the coercive field in the "superferromagnetic" state does not depend on measuring time. This time influences both T b and the temperature dependence of coercive field at T < T b . We corroborate our theoretical results by measurements on nanogranular films (CoFeB) x -(SiO 2 ) 1−x with concentration of ferromagnetic particles close, but below percolation threshold.

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Section: Results Of Modelingsupporting

confidence: 82%

“…To corroborate the above theoretical results experimentally, we perform magnetostatic measurements in the granular (CoFeB) x -(SiO 2 ) 1−x films [24,25]. In the samples under investigation, the FM nanoparticles were anisotropic with easy magnetization axes oriented along a certain direction in a film plane.…”

Section: Introductionmentioning

confidence: 65%

The influence of intergranular interaction on the magnetization of the ensemble of oriented Stoner–Wohlfarth nanoparticles

Timopheev

Ryabchenko

Каліта

et al. 2009

Journal of Applied Physics

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“…The electrical resistivity ρ(T) of a crystalline film is significantly lower as compared to that of an amorphous film [11,12]. While the crystalline films show a metallic behaviour, negative temperature coefficient of resistance has been reported for the amorphous or composite films [8,12]. Thus, the crystalline quality plays an important role in the process of electrical conduction of these films.…”

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confidence: 99%

Resistance minimum and electrical conduction mechanism in polycrystalline CoFeB thin films

Swamy¹,

Rout²,

Singh³

et al. 2015

J. Phys. D: Appl. Phys.

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The temperature dependent resistance R(T ) of polycrystalline ferromagnetic CoFeB thin films of varying thickness are analyzed considering various electrical scattering processes. We observe a resistance minimum in R(T ) curves below ≃ 29 K, which can be explained as an effect of intergranular Coulomb interaction in a granular system. The structural and Coulomb interaction related scattering processes contribute more as the film thickness decreases implying the role of disorder and granularity. Although the magnetic contribution to the resistance is the weakest compared to these two, it is the only thickness independent process. On the contrary, the negative coefficient of resistance can be explained by electron interaction effect in disordered amorphous films.

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“…CoFeB-reach film showed strong in-plane anisotropic magnetoresistance superimposed upon isotropic giant magnetoresistance (GMR), whereas CoFeB-poor sample possesses GMR effect only. 10 …”

Section: Samples Preparationmentioning

confidence: 99%

Ferromagnetic resonance, magnetic susceptibility, and transformation of domain structure in CoFeB film with growth induced anisotropy

Manuilov

Grishin

Munakata

2011

Journal of Applied Physics

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Field dependence of magnetic susceptibility in nanocrystalline CoFeB film was studied in a wide frequency range from 500 kHz to 15 GHz. Anomalies of the susceptibility were detected exciting CoFeB film with a solenoidal coil, microwave strip line, in the tunable microwave cavity as well as employing magneto-optical domains imaging. Critical spin fluctuations in the form of "soft" modes were observed in a whole range of orientations of magnetic field perpendicular to the "easy" magnetic axis. A sequence of domain structure transformations was extensively examined in a "hard" direction in in-plane magnetic field reduced below the field of uniaxial anisotropy H p ¼ 535 Oe. At first, uniformly magnetized state in CoFeB film transforms to stripe domains separated by low angle Néel domain walls (DWs) parallel to the "hard"-axis. Then, at critical field H cr ¼ 232 Oe, Néel DWs gradually convert to the"easy"-axis oriented Bloch DWs loaded with vertical Bloch lines (VBLs). After field reversal at H ¼ ÀH cr , backward conversion of VBL-loaded Bloch DWs to Néel DWs results in instantaneous energy release and sharp anomaly of magnetic susceptibility. Appearance of critical spin fluctuations accomplishes domains transformation to the uniformly magnetized state at H ¼ À535 Oe.

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Transport anisotropy in hetero-amorphous (CoFeB)–SiO2 thin films

Cited by 17 publications

References 8 publications

The influence of intergranular interaction on the magnetization of the ensemble of oriented Stoner–Wohlfarth nanoparticles

The influence of intergranular interaction on the magnetization of the ensemble of oriented Stoner–Wohlfarth nanoparticles

Resistance minimum and electrical conduction mechanism in polycrystalline CoFeB thin films

Ferromagnetic resonance, magnetic susceptibility, and transformation of domain structure in CoFeB film with growth induced anisotropy

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