Understanding fine magnetic particle systems through use of first-order reversal curve diagrams

Roberts, Andrew P.; Heslop, David; Zhao, Xiang; Pike, Christopher R.

doi:10.1002/2014rg000462

Cited by 355 publications

(358 citation statements)

References 140 publications

(525 reference statements)

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“…Type 2 samples seem to present coarser magnetite grains, as suggested by the FORC diagram on Fig. 6d showing PSD to MD magnetite (e. g., Roberts et al 2000;Roberts et al 2014). The most common feature in the analyzed samples is the occurrence for type 3 samples of high coercivity SD greigite (B c~6 0-65 mT) (Fig.…”

Section: Forc Diagramsmentioning

confidence: 73%

Rock magnetic characterization of ferrimagnetic iron sulfides in gas hydrate-bearing marine sediments at Site C0008, Nankai Trough, Pacific Ocean, off-coast Japan

Kars

Kodama

2015

Earth Planet Sp

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A high-resolution rock magnetic study was carried out in Integrated Ocean Drilling Program (IODP) Expedition 316 Hole C0008A located in the Megasplay Fault Zone of the Nankai Trough, SW offshore Japan, in order to document changes in magnetic properties throughout gas hydrate-bearing horizons. A total of 169 Pleistocene discrete samples were collected from~110 to 153 m core depth below sea floor (CSF), and their magnetic minerals concentration, grain size, composition, and rock magnetic parameters were estimated. Results showed the presence of iron oxides ((titano)-magnetite), iron sulfides (greigite and pyrrhotite), and their mixture, among which single-domain greigite is the most major magnetic mineral present in the samples. Two horizons containing ferrimagnetic iron sulfides (114.5-127.5 and 129.5-150 m CSF) covering almost the entire studied interval were identified, both associated with slight local pore water anomalies, suggesting occurrence of gas hydrates and anoxic conditions. These results are different from the neighboring Hole C0008C (215 m away from Hole C0008A) where four pore water anomalies and six iron sulfide-rich intervals were identified for the same time slice. Comparison of the lithology, physical properties, and geochemical data of the two boreholes at Site C0008 suggests that a combination of processes (e.g., availability of reactive iron, microbial activity) is responsible for such laterally varying distribution of the ferrimagnetic iron sulfides.

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Section: Forc Diagramsmentioning

confidence: 73%

Rock magnetic characterization of ferrimagnetic iron sulfides in gas hydrate-bearing marine sediments at Site C0008, Nankai Trough, Pacific Ocean, off-coast Japan

Kars

Kodama

2015

Earth Planet Sp

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“…5e, f). Here we diagnose each feature based on the description summarized by Roberts et al (2014). Sharp central ridges could be identified along horizontal lines at H u = 0 extending from ~15 mT to the maximum H c of 60 mT and further, which is indicative of non-interacting single-domain (titano)magnetite.…”

Section: Rock Magnetic Granulometry Of Volcanic Ashmentioning

confidence: 99%

Volcanic ash in bare ice south of Sør Rondane Mountains, Antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with SQUID gradiometer

Oda

Miyagi

Kawai

et al. 2016

Earth Planets Space

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Nondestructive magnetic detection of tephra layers in ice cores will be an important method to identify and correlate stratigraphic horizons of ice bearing volcanic ash particles. Volcanic ash particles were extracted from tephra-bearing ice samples collected from Nansen Ice Field south of the Sør Rondane Mountains, Antarctica. Particles are fresh glassy volcanic ash with diameters of ~50 μm, and chemical composition of the matrix glass belongs to a low-K basaltic andesite group, ranging from SiO 2 60-62 wt% and K 2 O 0.40-0.50 wt%. Considering the grain size of ash particles and chemical composition of volcanic glass, the ash in tephra-bearing ice samples might be originated from the South Sandwich Islands located 2800 km northwest of the sampling sites. Correlations on major element concentrations with tephra layers associated with South Sandwich Islands in EPICA-Dome C, Vostok, and Dome Fuji ice cores show high similarity. Rock magnetic experiments show that the magnetic mineral is pseudo-single-domain titanomagnetite with ulvospinel content of 0.2-0.35 mixed with single-domain to superparamagnetic (titano)magnetite. Small blocks of the tephra-bering ice were measured with a SQUID gradiometer at 1-mm intervals with a spatial resolution of ~3 mm. With DC magnetic field of 25 mT, magnetic signal could be enhanced and detected for all the samples including the one with invisible amount of tephra particles. In order to simulate a thin ash layer in ice core, volcanic ash particles extracted from the tephra-bearing ice were used to fabricate a thin ash layer, which were subsequently magnetized, measured with the gradiometer. The noise level for Z axis gradiometer was about 0.6 pT. Detection limit for a half-cylinder with 29 mm radius and a thickness of 1 mm uniformly magnetized in X axis direction is ~9 × 10

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“…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. The distribution of low coercivity component also showed spread along the H u axis, but the spread gradually decreases with increasing coercivity, which suggests pseudo-single domain (PSD) particles.…”

Section: Micro Samplementioning

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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Understanding fine magnetic particle systems through use of first-order reversal curve diagrams

Cited by 355 publications

References 140 publications

Rock magnetic characterization of ferrimagnetic iron sulfides in gas hydrate-bearing marine sediments at Site C0008, Nankai Trough, Pacific Ocean, off-coast Japan

Rock magnetic characterization of ferrimagnetic iron sulfides in gas hydrate-bearing marine sediments at Site C0008, Nankai Trough, Pacific Ocean, off-coast Japan

Volcanic ash in bare ice south of Sør Rondane Mountains, Antarctica: geochemistry, rock magnetism and nondestructive magnetic detection with SQUID gradiometer

Multiphase magnetic systems: Measurement and simulation

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