A high‐precision model of first‐order reversal curve (FORC) functions for single‐domain ferromagnets with uniaxial anisotropy

Newell, Andrew J.

doi:10.1029/2004gc000877

Cited by 115 publications

(183 citation statements)

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“…Preisach analysis and its descendant FORC analysis go a step further by mapping out a distribution of ''hysteron'' properties H c and H u which are interpreted as coercivity and interaction field, respectively [Roberts et al, 2000;Pike et al, 2001;Newell, 2005]. FORC distributions are purported to have some predictive value concerning behavior during ThellierThellier paleointensity experiments [Carvallo et al, 2005], but such predictions are at present qualitative in nature.…”

Section: Introductionmentioning

confidence: 99%

Characterizing the superparamagnetic grain distribution f(V, H_k) by thermal fluctuation tomography

et al. 2006

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[1] In 1965, D. J. Dunlop showed that the joint distribution of particle volumes and microcoercivities f(V, H k0 ) can be determined for magnetically monomineralic, thermally stable single-domain (SSD) ensembles by taking advantage of the joint temperature and field dependence of relaxation time. We have developed a procedure that follows Dunlop's strategy to obtain f(V, H k0 ) for ensembles containing both superparamagnetic and SSD grains, based on backfield remanence curves measured over a range of temperatures. Each point on the derivative curves represents the integrated contribution from grains that lie along a corresponding blocking contour on the Néel plot. A suitable set of such line integral samples can be used to reconstruct the f(V, H k0 ) distribution using the methods of tomographic imaging. Samples of the basal Tiva Canyon Tuff have narrow size distributions of elongate Ti-poor titanomagnetite. Tomographic inversion of the low-temperature backfield spectra yield sharply peaked f(V, H k0 ) distributions, from which we calculate modal grain dimensions in good agreement with those observed by transmission electron microscopy. Analysis of synthetic samples containing bimodal populations clearly distinguishes the two modes. Because our simplified forward calculations incompletely account for the effects of orientation distribution, the width of the coercivity distribution at each temperature is underestimated, and consequently, the inverse calculations yield grain distributions that are overly broad. Frequency-and temperature-dependent susceptibilities calculated for the inverted f(V, H k0 ) distributions accord fairly well with measured susceptibilities for the weakly interacting Tiva Canyon samples, less well for a moderately interacting paleosol specimen, and poorly for a strongly interacting ferrofluid.Citation: Jackson, M., B. Carter-Stiglitz, R. Egli, and P. Solheid (2006), Characterizing the superparamagnetic grain distribution f(V, H k ) by thermal fluctuation tomography,

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Section: Introductionmentioning

confidence: 99%

Characterizing the superparamagnetic grain distribution f(V, H_k) by thermal fluctuation tomography

et al. 2006

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“…Note that the FORC measurements used significantly smaller step sizes which did resolve multiple features. The concentric distribution at high coercivity suggests single domain (SD) particles, 25,26 and the large vertical spread of the high coercivity component suggests the interaction between these SD particles. 1,27 The bias to negative interaction (H u ) suggests mean field magnetizing interactions, 28 which would be expected from packed hexagonal plate 21 crystals.…”

Section: Micro Samplementioning

confidence: 99%

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confidence: 99%

Multiphase magnetic systems: Measurement and simulation

Cao

Ahmadzadeh

et al. 2018

Journal of Applied Physics

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Multiphase magnetic systems are common in nature and are increasingly being recognized in technical applications. One characterization method which has shown great promise for determining separate and collective effects of multiphase magnetic systems is first order reversal curves (FORCs). Several examples are given of FORC patterns which provide distinguishing evidence of multiple phases. In parallel, a visualization method for understanding multiphase magnetic interaction is given, which allocates Preisach magnetic elements as an input 'Preisach hysteron distribution pattern' (PHDP) to enable simulation of different 'wasp-waisted' magnetic behaviors. These simulated systems allow reproduction of different major hysteresis loop, FORC pattern, and switching field distributions of real systems and parameterized theoretical systems.The experimental FORC measurements and FORC diagrams of four commercially obtained magnetic materials, particularly those sold as nanopowders, shows that these materials are often not phase pure. They exhibit complex hysteresis behaviors that are not predictable based on relative phase fraction obtained by characterization methods such as diffraction. These multiphase materials, Even though the ideal characteristics of hysteresis in perfect single magnetic domains is generally accepted, it is still a challenge to interpret the hysteresis of real materials, as it depends on particle size, shape, and distribution, as well as stress, defects, and impurities. The hysteresis of magnetic mixtures is even more complex, as interactions between non-dilute phases distort the simple loop shape. However, the parameters extracted from major hysteresis loop -for instance, coercivityare not very efficient at showing the interactions of magnetic phases in a multiphase system. First order reversal curve (FORC) analysis is one technique which has developed rapidly in the last two decades, 1 providing a powerful tool for observing magnetic switching contributed by different magnetic phases. FORC is now applied to understand various hysteretic behaviors in metalinsulator transitions, 2 ferroelectricity, 3 magnetocalorics, 4 and perpendicular magnetic recording media. 5 The FORC technique can also be employed to distinguish the different magnetic signals in multiphase systems 4,6 to investigate subtle magnetic features caused by interaction of multiple magnetic phases.In this paper, a series of multiphase magnetic nanopowders are investigated experimentally using major hysteresis loops and FORC diagrams and these systems are also modeled using 'Preisach hysteron distribution patterns' (PHDPs) based on the classical Preisach model (CPM) to aid in descriptive understanding of the reduction of coercivity, or 'wasp-waistedness' features, observed in major loops of multiphase materials. The FORC diagrams of them generally indicate the existence of a low coercivity phase, a high coercivity phase, and a coupling region, which can all be simulated using PHDPs. Together, the simulations and measurements pr...

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“…It is wide spread in the geomagnetism and paleomagnetism sciences, [1][2][3] but is also used in thin film physics, 4 material sciences, and research into nanostructured systems. 5 Since the introduction of the scalar hysteresis model by Preisach 6 and further developments by Mayergoyz,7 theoretical description and mathematical modeling of FORC has significantly improved for particles, 8,9 multi-component samples, 10 or nanostructures 5 in recent years.…”

Section: Introductionmentioning

confidence: 99%

Application of magneto-optical Kerr effect to first-order reversal curve measurements

Gräfe

Schmidt

Audehm

et al. 2014

Review of Scientific Instruments

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Simple quadratic magneto-optic Kerr effect measurement system using permanent magnets Review of Scientific Instruments 88, 013901 (2017) First-order reversal curves (FORC) are a powerful method for magnetic sample characterization, separating all magnetic states of an investigated system according to their coercivity and internal magnetic interactions. A major drawback of using measurement techniques like VSM or SQUID, typically applied for FORC acquisition, is the long measurement time, limiting the resolution and the number of measurements due to time constraints. Faster techniques like MOKE result in problems regarding measurement stability over the curse of the acquisition of many minor loops, due to drift and non-absolute magnetization values. Here, we present an approach using a specialized field shape providing two anchor points for each minor loop for applying the magneto-optical Kerr effect (MOKE) technique to FORC measurements. This results in a high field resolution while keeping the total acquisition time to only a few minutes. MOKE FORC measurements are exemplarily applied to a simple permalloy film, an exchange-bias system, and a Gd/Fe multilayer system with perpendicular magnetic anisotropy, showcasing the versatility of the method. © 2014 AIP Publishing LLC.

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A high‐precision model of first‐order reversal curve (FORC) functions for single‐domain ferromagnets with uniaxial anisotropy

Cited by 115 publications

References 42 publications

Characterizing the superparamagnetic grain distribution f(V, H_k) by thermal fluctuation tomography

Characterizing the superparamagnetic grain distribution f(V, H_k) by thermal fluctuation tomography

Multiphase magnetic systems: Measurement and simulation

Application of magneto-optical Kerr effect to first-order reversal curve measurements

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A high‐precision model of first‐order reversal curve (FORC) functions for single‐domain ferromagnets with uniaxial anisotropy

Cited by 115 publications

References 42 publications

Characterizing the superparamagnetic grain distribution f(V, Hk) by thermal fluctuation tomography

Characterizing the superparamagnetic grain distribution f(V, Hk) by thermal fluctuation tomography

Multiphase magnetic systems: Measurement and simulation

Application of magneto-optical Kerr effect to first-order reversal curve measurements

Contact Info

Product

Resources

About

Characterizing the superparamagnetic grain distribution f(V, H_k) by thermal fluctuation tomography

Characterizing the superparamagnetic grain distribution f(V, H_k) by thermal fluctuation tomography