First order reversal curves and intrinsic parameter determination for magnetic materials; limitations of hysteron-based approaches in correlated systems

Ruta, Sergiu; Hovorka, Ondřej; Huang, Pin Wei; Wang, Kangkang; Ju, Ganping; Chantrell, R.W.

doi:10.1038/srep45218

Cited by 44 publications

(29 citation statements)

References 38 publications

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“…figure 4) that are difficult to interpret physically, and they complicate analysis of multiple component samples. Physically, these extra features cannot fully be due to the interaction fields, but they have been previously shown to be potentially from thermal fluctuations [51]. Other magnetic measurements, such as ferromagnetic resonance, have shown that interaction fields cause broadening and/or shifts of the P Hc peak [52][53][54][55], but not necessary inducing extra local minima/maxima.…”

Section: Resultsmentioning

confidence: 97%

Beyond the qualitative description of complex magnetic nanoparticle arrays using FORC measurement

Kouhpanji

Stadler

2020

Nano Ex.

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First-order reversal curve (FORC) measurements are broadly used for the characterization of complex magnetic nanostructures, but they can be inconclusive when quantifying the amount of different magnetic phases present in a sample. In this paper, we first establish a framework for extracting quantitative parameters from FORC measurements conducted on samples composed of a single type of magnetic nanostructure to interpret their magnetic properties. We then generalize our framework for the quantitative characterization of samples that are composed of 2-4 types of FeCo magnetic nanowires to determine the most reliable and reproducible parameters for a detailed analysis of samples. Finally, we conclude that the parameter with the best quantification potential, backfield remanence coercivity, does not require the full FORC measurement. Our approach provides an insightful path for fast, quantitative analysis of complex magnetic nanostructures, especially determination of the ratios of magnetic subcomponents present in multi-phase samples.

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Section: Resultsmentioning

confidence: 97%

Beyond the qualitative description of complex magnetic nanoparticle arrays using FORC measurement

Kouhpanji

Stadler

2020

Nano Ex.

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“…These coordinates are defined as follows In such a coordination system, h c represents the local coercive field of each hysteron, and h u corresponds to the local interaction field shifting the hysteron’s center along the field axis. 41 The obtained FORC distributions ρ( h c , h u ) for both ascending and descending magnetization branches, together with FORC curve families M ( H R , H ) plotted in canvas of the hysteresis loop, are shown in Figure 6 . In each FORC distribution, there are two main prominent features related to the irreversible magnetization switching processes.…”

Section: Results and Discussionmentioning

confidence: 99%

Magnetization Reversal Mechanism in Exchange-Biased Spring-like Thin-Film Composite

Perzanowski

Zarzycki

Gregor-Pawlowski

et al. 2020

ACS Appl. Mater. Interfaces

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Development of modern spintronic devices requires materials exhibiting specific magnetic effects. In this paper, we investigate a magnetization reversal mechanism in a [Co/Pd x ] 7 /CoO/[Co/Pd y ] 7 thin-film composite, where an antiferromagnet is sandwiched between a hard and a soft ferromagnets with different coercivities. The antiferromagnet/ferromagnet interfaces give rise to the exchange bias effect. The application of soft and hard ferromagnetic films causes exchange-spring-like behavior, while the choice of the Co/Pd multilayers provides large out-of-plane magnetic anisotropy. We observed that the magnitude and the sign of the exchange bias anisotropy field are related to the arrangement of the magnetic moments in the antiferromagnetic layer. This ordering is induced by the spin orientation present in neighboring ferromagnetic films, which is, in turn, dependent on the orientation and strength of the external magnetic field.

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“…It should be pointed out that in easy-axis NW arrays, the bias fields are positive [42,43]. In the mean-field framework [20,44,45], the interaction field H int is proportional to the magnetization den-sity: H int = kM/V = kPM s m, where k is a constant, m the reduced magnetization, P the film porosity and V the film volume. In the case of dipolar interactions, the demagnetizing field felt by a NW from the film mean magnetization density leads to k = +1/2 for the easy-plane case, instead of k = −1 for the easy-axis case [46,47].…”

Section: Coercive Field Distribution In the Easy Planementioning

confidence: 99%

Magnetoelastic effects and random magnetic anisotropy in highly strained ultrathin Ni nanowires epitaxied in a SrTiO3 matrix

Weng

Hennes

Hrabovský³

et al. 2020

Journal of Magnetism and Magnetic Materials

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We analyze the magnetic anisotropy of Ni nanowires with diameters smaller than 5 nm. The nanowires are vertically epitaxied in a SrTiO 3 (001) matrix which generates huge tensile strains up to 3.6% along the nanowire axis. This leads to an unusual anisotropy, characterized by an easy magnetization plane perpendicular to the nanowire axis. Hysteresis cycles M(H) unveil an overall in-plane isotropy, while an opening of the M(H) cycles and thermal activation measurements indicate the presence of local energy barriers inside the nanowires. Surprisingly, the coercive field H c (T) decays exponentially with increasing temperature, for both the easy plane and the hard axis. Based on these findings, we provide an analysis of magnetoelastic effects in the nanowires. By considering global averaging over the anisotropy distribution and local averaging according to the Random Magnetic Anisotropy model, we find that the global anisotropy, with its hard axis and isotropic easy plane, is related to the mean strain, while coercivity arises from local strain variations. We evidence that a thermally activated anisotropy softening occurs in the nanowires, in addition to Sharrock's law of thermal reduction of coercivity. Possible mechanisms responsible for this thermal softening of anisotropy are proposed and discussed. Our study eventually allows to identify two major competing effects at play in the present system: an increasing magnetic anisotropy with increasing strain and a reduction of the anisotropy with increasing local strain fluctuations.

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First order reversal curves and intrinsic parameter determination for magnetic materials; limitations of hysteron-based approaches in correlated systems

Cited by 44 publications

References 38 publications

Beyond the qualitative description of complex magnetic nanoparticle arrays using FORC measurement

Beyond the qualitative description of complex magnetic nanoparticle arrays using FORC measurement

Magnetization Reversal Mechanism in Exchange-Biased Spring-like Thin-Film Composite

Magnetoelastic effects and random magnetic anisotropy in highly strained ultrathin Ni nanowires epitaxied in a SrTiO3 matrix

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