Magnetic anisotropy and coercivity of ultrafine iron particles

Hou, Denglu; Nie, Xin; Luo, Hao

doi:10.1016/s0304-8853(98)00170-x

Cited by 27 publications

(16 citation statements)

References 8 publications

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“…From the hysteresis loop, an anisotropy energy of K 1 % 3.772 Â 10 5 erg/cm 3 was estimated according to the law of approach to saturation (LATS). 21 This value is ca. 3.2 times larger than that of the bulk Fe 3 O 4 ($1.18 Â 10 5 erg/cm 3 ), and it is ca.…”

Section: Resultsmentioning

confidence: 96%

Discovery of hard-magnetic domains in two-dimensional arrays of soft-magnetic Fe3O4 nanocubes

Sun

Wang

et al. 2015

Journal of Applied Physics

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In this study, abnormal hard-magnetic domains were discovered in Fe3O4@C composite material, in which well-ordered 16-nm-sized Fe3O4 cubes were tightly embedded into carbon sheets of tens of nanometers thick. It was found that ca. 40 columns of Fe3O4 nanocubes magnetically self-assembled into a single strip-type domain with perpendicular magnetic anisotropy. More strikingly, remarkable domain misalignments, which were very similar to common edge dislocations among atomic planes in crystal lattices, were clearly observed and termed as “domain dislocation” in this work. The hard-magnetic properties of Fe3O4@C material, including large coercivity of 2150 Oe, high MR/MS value of 0.9, and strong anisotropy energy of 3.772 × 105 erg/cm3, were further ascertained by carefully designed electromagnetic absorption contrast experiments. It is anticipated that the discovery of hard-magnetic domains and domain dislocations within 2-D arrays of soft-magnetic nanomaterials will shed new light on the development of high-density perpendicular magnetic recording industry.

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Section: Resultsmentioning

confidence: 96%

Discovery of hard-magnetic domains in two-dimensional arrays of soft-magnetic Fe3O4 nanocubes

Sun

Wang

et al. 2015

Journal of Applied Physics

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“…are determined from the hysteresis loops in Fig. 6 on the basis of the law of approach to saturation (LATS), 11 are also listed in Table III. It is clear that, except for the calculated M s values based on MAR, other calculated M s values are in excellent consistency with the measured ones, evidencing the presence of static dephasing behaviors in dextran and SDS cases and echo-limited behavior in the SHMP case.…”

Section: Resultsmentioning

confidence: 99%

Impact of dispersants on relaxivities of magnetite contrast agents

Cheng

Chen

2015

Journal of Applied Physics

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Particle size is normally thought to be a major factor to evaluate MRI performance of contrast agents in biological systems. In this regard, three size-relevant regimes, including motional averaging regime, static dephasing regime, and echo-limited regime, have been well developed. In this study, we find the dispersant, which is often used as the subordinate additive in MRI measurements, is another key factor that determines the application of these three regimes in real systems. Our results show that the identically sized particle systems can separately exhibit static dephasing and echo-limited behaviors merely by altering the dispersants in aqueous solution.

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“…where M is the magnetization, μ 0 is permeability of free space, M s is the saturation magnetization, H is the applied magnetic field, κ is the forced magnetization, and the constant (8/105) is the first-order anisotropy in randomly oriented polycrystalline materials [Hou 1998b, Ranvah 2008]. The effective magnetic anisotropy K E is dictated by several features: K 2 E = K 2 sh + K 2 st + K 2 sur + 2 7 K 2 mc , where K sh , K st , K sur , and K mc are the shape, stress, surface, and magnetoctrystalline anisotropy, respectively [Hou 1998a, Hou 1998b].…”

Section: Resultsmentioning

confidence: 99%

“…In this analysis, the magnetic anisotropy is determined in high field regimes (H H c ). The LATS model is given as [Yang 1996, Chikazumi 1997, Hou 1998a, Hou 1998b, Ranvah 2008]…”

Section: Resultsmentioning

confidence: 99%

“…Researchers have previously reported that an effective magnetic anisotropy K E incorporating all of these energies can be measured using magnetization saturation curves over broad temperature regimes [Chikazumi 1997, Hou 1998a, Hou 1998b, Ranvah 2008 using the law of approach to saturation (LATS) method. In this letter, the measurements of effective magnetic anisotropy K E as a function of temperature are correlated with magnetodielectric MD constant measurements for a Fe 2 O 3 particulate epoxy composite.…”

Section: Introductionmentioning

confidence: 99%

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Magneto-dielectric and magnetic anisotropy maxima in γ-Fe₂O₃nanocomposite

et al. 2013

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The temperature dependence of the magneto-dielectric (MD) response in polycrystalline γ -Fe 2 O 3 nanoparticulates embedded in an epoxy resin has been experimentally investigated. A maximum in the MD coefficient (∼ 9%) occurs at ∼200 K, which is well below its Curie point (T c ∼ 948 K) and blocking temperature (T B = 310 K). The law of approach to saturation technique was used to measure the effective magnetic anisotropy K E over a broad temperature range. A maximum in the effective magnetic anisotropy appears at ∼200 K. The correlation between the maxima in K E and MD suggests that magnetic anisotropy may play a role in designing improved magneto-dielectric coupling in single-phase magnetic materials at the nanoscale.Index Terms-Magneto-electronics, γ -Fe 2 O 3 nanocomposite, magneto-dielectric, magnetic anisotropy, law of approach to saturation.

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Magnetic anisotropy and coercivity of ultrafine iron particles

Cited by 27 publications

References 8 publications

Discovery of hard-magnetic domains in two-dimensional arrays of soft-magnetic Fe3O4 nanocubes

Discovery of hard-magnetic domains in two-dimensional arrays of soft-magnetic Fe3O4 nanocubes

Impact of dispersants on relaxivities of magnetite contrast agents

Magneto-dielectric and magnetic anisotropy maxima in γ-Fe₂O₃nanocomposite

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Magnetic anisotropy and coercivity of ultrafine iron particles

Cited by 27 publications

References 8 publications

Discovery of hard-magnetic domains in two-dimensional arrays of soft-magnetic Fe3O4 nanocubes

Discovery of hard-magnetic domains in two-dimensional arrays of soft-magnetic Fe3O4 nanocubes

Impact of dispersants on relaxivities of magnetite contrast agents

Magneto-dielectric and magnetic anisotropy maxima in γ-Fe2O3nanocomposite

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Product

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Magneto-dielectric and magnetic anisotropy maxima in γ-Fe₂O₃nanocomposite