Structure and magnetic properties of iron–platinum particles with γ-ferric-oxide shell

Basit, Lubna; Nepijko, S. A.; Shukoor, Ibrahim; Ksenofontov, Vadim; Klimenkov, M.; Fecher, Gerhard H.; Schönhense, G.; Tremel, Wolfgang; Felser, Claudia

doi:10.1007/s00339-008-4874-7

Cited by 6 publications

(5 citation statements)

References 29 publications

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“…To obtain such particles will make an improved selection of smaller sized particles necessary. Actually, the embedding in silica has the advantage of preventing oxidation of the particles as observed for FePt [25]. Its disadvantage is, indeed, that the size selection is not well controllable.…”

Section: Resultsmentioning

confidence: 99%

Heusler compounds as ternary intermetallic nanoparticles: Co₂FeGa

Basit

Wang

Jenkins

et al. 2009

J. Phys. D: Appl. Phys.

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This work describes the preparation of ternary nanoparticles based on the Heusler compound Co2FeGa. Nanoparticles with sizes of about 20 nm were synthesized by reducing a methanol impregnated mixture of CoCl2 · 6H2O, Fe(NO3)3 · 9H2O and Ga(NO3)3 · xH2O after loading on fumed silica. The dried samples were heated under pure H2 gas at 900 °C. The obtained nanoparticles—embedded in silica—were investigated by means of x-ray diffraction (XRD), transmission electron microscopy, temperature dependent magnetometry and Mößbauer spectroscopy. All methods clearly revealed the Heusler-type L21 structure of the nanoparticles. In particular, anomalous XRD data demonstrate the correct composition in addition to the occurrence of the L21 structure. The magnetic moment of the particles is about 5μB at low temperature in good agreement with the value of bulk material. This suggests that the half-metallic properties are conserved even in particles on the 10 nm scale.

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Section: Resultsmentioning

confidence: 99%

Heusler compounds as ternary intermetallic nanoparticles: Co₂FeGa

Basit

Wang

Jenkins

et al. 2009

J. Phys. D: Appl. Phys.

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“…Interestingly, currently, there is an increasing interest in, so-called, inverted structures (see Fig. 1), where the shell is FM or ferrimagnetic (FiM) and the core is AFM, containing for example Mn oxides12131415161718, Fe oxides1920212223242526272829, Co oxides30313233343536, Cr oxides373839, metallic FePt40 or even multiferroic BiFeO 3 (Refs. 41,42).…”

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confidence: 99%

“…It has been demonstrated, experimentally and theoretically, that the poor crystallinity of the AFM counterpart can result in considerably inferior exchange bias properties4344. In fact, inverted structures have already demonstrated very large coercivities and loop shifts, tunable blocking temperatures, enhanced Néel temperatures or proximity effects12131415161718192021222324252627282930313233343536373839404142 and have been proposed as potential magnetoelectric random access memories41. However, despite their potential, systematic studies of size effects (i.e., core diameter or shell thickness) are still rather scarce12162225333435.…”

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confidence: 99%

Enhanced Magnetic Properties in Antiferromagnetic-Core/Ferrimagnetic-Shell Nanoparticles

Vasilakaki

Trohidou

Nogués

2015

Sci Rep

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Bi-magnetic core/shell nanoparticles are gaining increasing interest due to their foreseen applications. Inverse antiferromagnetic(AFM)/ferrimagnetic(FiM) core/shell nanoparticles are particularly appealing since they may overcome some of the limitations of conventional FiM/AFM systems. However, virtually no simulations exist on this type of morphology. Here we present systematic Metropolis Monte Carlo simulations of the exchange bias properties of such nanoparticles. The coercivity, HC, and loop shift, Hex, present a non-monotonic dependence with the core diameter and the shell thickness, in excellent agreement with the available experimental data. Additionally, we demonstrate novel unconventional behavior in FiM/AFM particles. Namely, while HC and Hex decrease upon increasing FiM thickness for small AFM cores (as expected), they show the opposite trend for large cores. This presents a counterintuitive FiM size dependence for large AFM cores that is attributed to the competition between core and shell contributions, which expands over a wider range of core diameters leading to non-vanishing Hex even for very large cores. Moreover, the results also hint different possible ways to enhance the experimental performance of inverse core/shell nanoparticles for diverse applications.

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“…Because of this magnetic nature, ferrites are considered as one of the most fascinating inorganic magnetic materials because of the occurrence of various types of structures, compositions as well as properties [1-6, 17-19, 21, 25, 26]. Presently, there is a growing interest in magnetic materials exhibiting inverted structures due to their novel properties and these structures are found in bi-magnetic oxide NPs [2,27], metallic NPs [28] or perovskite NPs [29]. Based on the transition temperature of the magnetic materials (i.e., Curie temperature, T c and Néel temperature, T N ), there are two main types of inverted structures [30]: singly inverted (T c > T N ), e.g., FeO/Fe 3 O 4, and doubly inverted (T N > T c ), e.g., MnO/Mn 3 O 4 .…”

Section: Introductionmentioning

confidence: 99%

Effect of size, phase fraction and interface coupling on the magnetic behavior of al-modified α-Fe2O3/NiFe2O4 core–shell structure

et al. 2021

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The effect of Al doping on the NiFe 2 O 4 phase for the enhanced magnetic properties of α-Fe 2 O 3 /NiFe 2 O 4 composite has been reported. The crystalline quality of the samples improves significantly with increasing Al doping concentration. The formation of core-shell structure in the samples along with the reduction in shell thickness with Al doping has been evidenced through morphological characterization. All the samples show the optical band gap value of 1.7 eV that could produce higher efficiency toward the visible light absorption. All the samples show the doubly inverted structure (T N > T c ). The low saturation magnetization and high coercivity in the Al-doped samples in comparison with the un-doped sample are observed because of the paramagnetic spin configuration of Al ions and interface coupling between α-Fe 2 O 3 and NiFe 2 O 4 phases. The different exchange coupling in Al-modified α-Fe 2 O 3 /NiFe 2 O 4 composite systems could be associated with the NiFe 2 O 4 phase. The occurrence of narrow band gap, ferromagnetism, loop shift, freezing temperature and doubly inverted structure in the nanocomposite samples could be beneficial for photo-electrochemical water splitting, photo-catalyst and magnetic memory device applications. KeywordsNanocomposite • NiFe 2 O 4 • Core-shell structure • Exchange bias • Doubly inverted structure * P. Mallick

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Structure and magnetic properties of iron–platinum particles with γ-ferric-oxide shell

Cited by 6 publications

References 29 publications

Heusler compounds as ternary intermetallic nanoparticles: Co₂FeGa

Heusler compounds as ternary intermetallic nanoparticles: Co₂FeGa

Enhanced Magnetic Properties in Antiferromagnetic-Core/Ferrimagnetic-Shell Nanoparticles

Effect of size, phase fraction and interface coupling on the magnetic behavior of al-modified α-Fe2O3/NiFe2O4 core–shell structure

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Structure and magnetic properties of iron–platinum particles with γ-ferric-oxide shell

Cited by 6 publications

References 29 publications

Heusler compounds as ternary intermetallic nanoparticles: Co2FeGa

Heusler compounds as ternary intermetallic nanoparticles: Co2FeGa

Enhanced Magnetic Properties in Antiferromagnetic-Core/Ferrimagnetic-Shell Nanoparticles

Effect of size, phase fraction and interface coupling on the magnetic behavior of al-modified α-Fe2O3/NiFe2O4 core–shell structure

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Product

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Heusler compounds as ternary intermetallic nanoparticles: Co₂FeGa

Heusler compounds as ternary intermetallic nanoparticles: Co₂FeGa