Obtaining the anisotropy axes misalignment and dispersion in exchange bias systems by magnetoresistance

Siqueira, J.V. de; Silva, O.E. da; Kern, P.R.; Gazola, João Paulo; Carara, M.; Rigue, Josué Neroti

doi:10.1016/j.jmmm.2019.01.075

Cited by 3 publications

(5 citation statements)

References 24 publications

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“…Previously, we reported studies on EB systems through the use of different techniques [magnetization measurements, torque measurements and anisotropic magnetoresistance], in which very good agreement between the very same phenomenological model and proper experimental data was obtained [36][37][38]. We have detailed protocols and indicated the sensitivity with which each technique reveals the different parameters linked to the EB phenomenon, highlighting the origins of asymmetries in the curves measured by different techniques.…”

Section: Introductionmentioning

confidence: 74%

Asymmetric magnetoimpedance in exchange-biased systems

Gazola,

Santos,

de Andrade

et al. 2024

J. Phys.: Condens. Matter

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Magnetic systems with competing anisotropies generally exhibit asymmetry between the maximum amplitudes of the right and left maxima of the magnetoimpedance curve. Small errors in positioning the samples at the experimental setup may also produce such asymmetry. In this work, we present a study on the sources of the asymmetry between magnetoimpedance peaks in systems that present the Exchange Bias phenomenon, by comparing a phenomenological model to experimental data. A set of samples with different repetitions of the NiFe/FeMn exchange-biased bilayer was used in this study. From the frequency evolution of the asymmetry, together with magnetization curves, we were able to identify the sources for the observed magnetoimpedance asymmetry found on our experimental data.

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Section: Introductionmentioning

confidence: 74%

Asymmetric magnetoimpedance in exchange-biased systems

Gazola,

Santos,

de Andrade

et al. 2024

J. Phys.: Condens. Matter

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“…These effects also enhance the misalignment of anisotropy easy axes in AF layer. Several experimental works have reported the influence of the AF easy axis dispersion which causes an increase [20,22] or decrease [21] of H EB . These show that the effect of AF easy axis misalignment on H EB is still unclear.…”

Section: The Effect Of Easy Axis Distributionsmentioning

confidence: 99%

“…They found that the increase of IrMn thickness causes an increase of AF easy axis distribution leading to a reduction of H EB at larger dispersion angle. From the several reports, these show that the effect of AF easy axis misalignment on H EB is still unclear by no change [14], decrease [21], or increase H EB [20,22] when the film thickness of AF changing. Therefore, it is necessary to study the effect of easy axis dispersion on the variation of H EB in the bilayers system in order to understand its role and physical mechanism behind the complex exchange bias phenomena.…”

Section: Introductionmentioning

confidence: 99%

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Micromagnetic model of exchange bias: effects of structure and AF easy axis dispersion for IrMn/CoFe bilayers

Daeng-am¹,

Chureemart²,

Rittidech³

et al. 2019

J. Phys. D: Appl. Phys.

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A micromagnetic model of an exchange bias bilayer is used to examine the impact of the physical structure and the easy axis dispersion of the antiferromagnetic (AF) layer on the exchange bias field (H EB) in an IrMn/CoFe system. Because of the different timescales, the magnetization dynamics of the IrMn and CoFe layers are modelled using respectively a kinetic Monte Carlo (kMC) approach and Landau-Lifshitz-Gilbert (LLG) equation. The easy axis dispersion is modelled using a Gaussian distribution. The calculations show that H EB increases with increasing IrMn thickness and grain size, in agreement with experimental work. Moreover, the model allows the visualization of the switching process at the micromagnetic level to reveal the reversal mechanism. We find that the effect of AF easy axis distribution not only strongly affects the reduction of H EB but also drives non-coherent behaviour in the reversal mechanism. This confirms that the easy axis distribution is an important factor with strong impact on the magnetic properties and exchange bias field of an exchange bias system.

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“…Although known for decades, characterization of fundamental properties remains an active area of research, as the precise origins of exchange bias are not completely understood [7]. Exchange anisotropy has been extensively studied through a number of techniques, including hysteresis and torque magnetometry [1], ferromagnetic resonance (FMR) [8], first-order reversal curve [9,10], anisotropic magnetoresistance [11], and reversible susceptibility [12], among others.…”

Section: Introductionmentioning

confidence: 99%

Critical curves in NiFe/FeMn bilayers with varying antiferromagnetic layer thickness

Adams¹,

Cimpoesu²,

Benit³

et al. 2021

J. Phys. D: Appl. Phys.

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The effect of antiferromagnetic (AF) layer thickness on exchange bias was studied in a series of NiFe(50 nm)/FeMn(t) bilayers through both irreversible and reversible experiments at room temperature. The exchange bias was evaluated in the sample plane both through measurement of the major hysteresis loops and probing the reversible susceptibility. The critical curve was constructed to map the angular dependence of the magnetization switching and exchange bias, which is found to evolve as a function of AF layer thickness. Ferromagnetic resonance absorption was measured at several frequencies and angles, and angular-dependent absorption curves were plotted. A comparison is made between the recorded exchange bias using the three methods. The measurements reported are supported by simulations under a generalized Stoner–Wohlfarth model, and general limitations of the experiment are discussed.

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Obtaining the anisotropy axes misalignment and dispersion in exchange bias systems by magnetoresistance

Cited by 3 publications

References 24 publications

Asymmetric magnetoimpedance in exchange-biased systems

Asymmetric magnetoimpedance in exchange-biased systems

Micromagnetic model of exchange bias: effects of structure and AF easy axis dispersion for IrMn/CoFe bilayers

Critical curves in NiFe/FeMn bilayers with varying antiferromagnetic layer thickness

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