Magnetization process of cubic Fe3O4 submicron particles: First-order reversal curves and neutron diffraction studies

Kobayashi, Satoru; Nomura, Eiji; Noda, Chiaki; Manjanna, Jayappa; Jargalan, Narmandakh; Uyanga, Enkhnaran; Bobrikov, Ivan; Kiseleva, Tatiana; Rusakov, Vyacheslav; Sangaa, Deleg

doi:10.1016/j.jmmm.2023.171509

Cited by 2 publications

(1 citation statement)

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“…The positive peaks collapse onto the B u axis as the particle size increases to form true VNAPs (Figure 4f), and suggests that the SD to SV transition becomes a more reversible process at larger oblate particles sizes. These mirrored positive peaks either side of the B c axis are often referred to as the butterfly FORC structure, highly indicative of SV states and commonly observed in high anisotropy monoclinic systems such as magnetite at low temperatures (Kobayashi et al., 2023; Smirnov, 2006) or high basal plane shape anisotropies of iron and cobalt platelets (Chiba et al., 2020; Dumas et al., 2007; Pike & Fernandez, 1999). For AR ∼ 0.25 (Figure 4i), the butterfly structures still exist, but for larger sizes, that is,

{ >}

185 nm, these disappear and NPNP or NPN structures arise.…”

Section: Simulated Forc Diagrams For Random Distributionsmentioning

confidence: 94%

Micromagnetic Determination of the FORC Response of Paleomagnetically Significant Magnetite Assemblages

Nagy,

Moreno,

Muxworthy

et al. 2024

Geochem Geophys Geosyst

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Micromagnetic modeling allows the systematic study of the effects of particle size and shape on the first‐order reversal curve (FORC) magnetic hysteresis response for magnetite particles in the single‐domain (SD) and pseudo‐single domain (PSD) particle size range. The interpretation of FORCs, though widely used, has been highly subjective. Here, we use micromagnetics to model randomly oriented distributions of particles to allow more physically meaningful interpretations. We show that one commonly found type of PSD particle—namely the single vortex (SV) particle—has far more complex signals than SD particles, with multiple peaks and troughs in the FORC distribution, where the peaks have higher switching fields for larger SV particles. Particles in the SD to SV transition zone have the lowest switching fields. Symmetrical and prolate particles display similar behavior, with distinctive peaks forming near the vertical axis of the FORC diagram. In contrast, highly oblate particles produce “butterfly” structures, suggesting that these are potentially diagnostic of particle morphology. We also consider FORC diagrams for distributions of particle sizes and shapes and produce an online application that users can use to build their own FORC distributions. There is good agreement between the model predictions for distributions of particle sizes and shapes, and the published experimental literature.

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