Fabrication and enhanced magnetoresistance of SiO2-coated Fe3O4 nanosphere compact

Wang, Junfeng; Shi, Jing; Tian, Decheng; Deng, Hong; Li, Yadong; Song, Pengyun; Chen, Chinping

doi:10.1063/1.2741612

Cited by 33 publications

(20 citation statements)

References 33 publications

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“…In most cases, the obtained MR values are much lower than that of theory prediction, especially at high temperature. The rapid decrease of the MR with temperature increasing was mostly attributed to the loss of spin polarization or increase of the higher order inelastic hopping of electrons through the localized states [1,6]. However, none of the proposed models can explain all the phenomena observed in the experiments.…”

Section: Introductionmentioning

confidence: 77%

“…The former one has a nearly linear MR behavior in a large field range [3], while the later shows a quick decrease of MR in a very small field corresponding to a tunneling magnetoresistance (TMR) [6]. However, it is still amazing to observe the two different mechanisms in the pure magnetite, even in the same sample [7].…”

Section: Introductionmentioning

confidence: 97%

“…Variety forms of Magnetite has been extensively studied including crystal [2], pressed powders [3], epitaxial and polycrystal films [4], magnetic tunneling junctions [5] and some composite granular systems [6]. In most cases, the obtained MR values are much lower than that of theory prediction, especially at high temperature.…”

Section: Introductionmentioning

confidence: 98%

“…However, it is still amazing to observe the two different mechanisms in the pure magnetite, even in the same sample [7]. Indeed, defects (or impurities) and the surface states of the ferromagnetic grains are responsible for the result of the spin-dependent transport [1,6]. To better understand the mechanism of MR behavior in the pure magnetite sample, we have prepared nearly monodisperse Fe 3 O 4 of $50 nm by a chemical route and investigated the MR effect of the granular system.…”

Section: Introductionmentioning

confidence: 98%

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Interface scattering and spin-dependent transport in granular magnetite

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2009

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Section: Introductionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

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Interface scattering and spin-dependent transport in granular magnetite

Yang

Zhu

2009

Journal of Magnetism and Magnetic Materials

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“…Secondly, the magnetic Fe 3 O 4 particles were coated with silica according to the sol-gel method [22]. The as-prepared magnetic Fe 3 O 4 particles (approximate 0.3 g) were dispersed in a 40 mL isopropanol with the aid of ultrasonication.…”

Section: Preparation Of Mim-mpsmentioning

confidence: 99%

N-Methylimidazolium modified magnetic particles as adsorbents for solid phase extraction of genomic deoxyribonucleic acid from genetically modified soybeans

Deng

Jiang

2013

Analytica Chimica Acta

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The Effect of Thickness‐Tunable ZrO₂ Shell on Enhancing the Tunneling Magnetoresistance of Fe₃O₄ Supraparticles

Xie

et al. 2018

Adv Materials Inter

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at room temperature. This degradation is caused admittedly by the reduced spin polarization due to the multiple effects of oxidation, defects, bonding, and surface reconstruction at the surfaces or interfaces of the polycrystal grain boundaries. Comparing to bulk materials, the nanoparticles can produce enhanced extrinsic MR owing to the effect of spin-dependent interface scattering or tunneling through the boundaries. [18] Additionally, the MR can still be increased by core-shell encapsulated structures. For example, an insulating shell coats on the magnetite core. In such a dielectric system, nanometric ferromagnetic particles show giant TMR by spin-dependent tunneling of conducting electrons at the magneticinsulator interfaces. Electrons with spin parallel to the particle magnetization have a bigger probability of tunneling than electrons with antiparallel spin, resulting in an overall lower resistance. Similar MR enhancement has been realized in Fe 3 O 4 @SiO 2 , [19] Fe 3 O 4 @ oleic acid, [20] Fe@Cr, [21] and Fe 3 O 4 @ZnS [22] system. Insulator zirconium dioxide (ZrO 2 ) is a nonmetallic inorganic material and has excellent resistance to acids and alkalis. It was widely applied in catalyst carrier and thermal barrier fields due to the stability and insulativity. Previous studies have shown that ZrO 2 doping in the perovskite systems can effectively enhance the magnetoresistance. [23][24][25] To the best of our knowledge, it is still unexploited of ZrO 2 doping in the half-metal Fe 3 O 4 nanoparticles by means of the core-shell structural system.In this paper, Fe 3 O 4 @ZrO 2 core-shell nanocomposites are prepared with controllable shell thickness and core-size. The pomegranate-like core is obtained and composed of several monocrystals and single-domain Fe 3 O 4 nanocrystals with size <10 nm. The magnetic structure and magnetotransport property of the core-shell nanocomposites are explored. Our results show that the MR is increased to ≈7.5% at 2 kOe in this core-shell system compared to that of pure Fe 3 O 4 nanoparticles ≈4.7%. Moreover, as Zr content increases, the MR first increases and then decreases. This is because the addition of insulated barrier promotes the tunneling effect, which enhances the MR, but with further increase of ZrO 2 thickness, the barrier becomes larger and the electron tunneling becomes difficult, leading to the reduced MR. In addition, the results of Fe 3 O 4 @ZrO 2 with different core sizes show that the MR rises monotonically with a decrease of the size of core. Moreover, for eliminate the possible effect of ZrO 2 permeating into the interior of the pomegranate-like core, fault-cutting is prepared andThe core-shell Fe 3 O 4 @ZrO 2 nanoparticles with controllable shell thickness and core dimensions are synthesized using solvothermal approaches. The introduction of the insulator ZrO 2 shell allows realizing the enhancement of tunneling magnetoresistance (TMR) effect of the functional nanomaterials. The influences of temperature, magnetic field, and shell thickness on the TMR are ...

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Fabrication and enhanced magnetoresistance of SiO2-coated Fe3O4 nanosphere compact

Cited by 33 publications

References 33 publications

Interface scattering and spin-dependent transport in granular magnetite

Interface scattering and spin-dependent transport in granular magnetite

N-Methylimidazolium modified magnetic particles as adsorbents for solid phase extraction of genomic deoxyribonucleic acid from genetically modified soybeans

The Effect of Thickness‐Tunable ZrO₂ Shell on Enhancing the Tunneling Magnetoresistance of Fe₃O₄ Supraparticles

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Fabrication and enhanced magnetoresistance of SiO2-coated Fe3O4 nanosphere compact

Cited by 33 publications

References 33 publications

Interface scattering and spin-dependent transport in granular magnetite

Interface scattering and spin-dependent transport in granular magnetite

N-Methylimidazolium modified magnetic particles as adsorbents for solid phase extraction of genomic deoxyribonucleic acid from genetically modified soybeans

The Effect of Thickness‐Tunable ZrO2 Shell on Enhancing the Tunneling Magnetoresistance of Fe3O4 Supraparticles

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The Effect of Thickness‐Tunable ZrO₂ Shell on Enhancing the Tunneling Magnetoresistance of Fe₃O₄ Supraparticles