Magnetism of iron oxide based core-shell nanoparticles from interface mixing with enhanced spin-orbit coupling

Skoropata, Elizabeth; Desautels, R. D.; Chi, Cheng–Chung; Ouyang, Hao; Freeland, J. W.; Lierop, J. van

doi:10.1103/physrevb.89.024410

Cited by 52 publications

(35 citation statements)

References 41 publications

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“…The lattice parameter of the spinel phase was typical for c-Fe 2 O 3 or doped-c-Fe 2 O 3 nanoparticles, 13,14 and the rock-salt phase was consistent with MnO. 15 The slightly altered lattice parameter and larger fraction of spinel (core) vs. rock-salt (shell) fractions in comparison with other core shell systems we have examined using comparable shell thicknesses (a $24% increase) 4,9,16 were consistent with a larger amount of core-shell intermixing.…”

Section: Resultsmentioning

confidence: 70%

“…As such, substantial interest has been aimed at identifying and understanding the role of magnetic interactions at the core-shell interface, and the identification and characterization of interfacial intermixed layers within core-shell nanoparticles. [1][2][3][4][5][6][7][8][9] Of critical importance is to understand the nominal core and shell intrinsic magnetism and intermixing effects on the resulting dynamical magnetism. To examine this, we have synthesized and characterized the structure, composition, and dynamical magnetism of c-Fe 2 O 3 /MnO core-shell nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

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Examination of the magnetism dynamics from intermixing effects in γ-Fe2O3/MnO core-shell nanoparticles

Skoropata

Ouyang

et al. 2015

Journal of Applied Physics

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We have examined the effects of core-shell intermixing on the dynamical magnetism of γ-Fe2O3/MnO nanoparticles. The core and shell phases were identified using x-ray diffraction, and x-ray absorption spectroscopy identified Mn ions in both octahedral and tetrahedral sites, consistent with a significant amount of substitution at the core-shell interface to form an Fe/Mn-ferrite. The dynamical response was probed by Mössbauer spectroscopy, which decouples surface and core spins, and suggested a change in the relaxation behaviour among the spin populations within γ-Fe2O3/MnO relative to the γ-Fe2O3 seed particles. Interestingly, the magnetic relaxation effects at the atomic scale, measured via Mössbauer spectroscopy, were enhanced, indicating that the addition of an MnO shell and intermixing affected the dynamical freezing process which altered the surface magnetism of the γ-Fe2O3 core. Our results show that both the MnO shell and the interfacial intermixed layer are important in determining the core-shell nanoparticle magnetism.

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Section: Resultsmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Examination of the magnetism dynamics from intermixing effects in γ-Fe2O3/MnO core-shell nanoparticles

Skoropata

Ouyang

et al. 2015

Journal of Applied Physics

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“…Such results have some precedent in the literature. In the case of γ –Fe 2 O 3 , Skoropata et al have recently reported a strong increase in the orbital moment for iron in the outer shell of core-shell nanoparticles doped with cobalt 13 . For stoichiometric Fe 3 O 4 , Huang et al reported orbital moments of 0.67 ± 0.07 μ B at all temperatures measured using XMCD 10 , while Li et al inferred a large orbital magnetic moment of 0.51 ± 0.05 μ B at 10 K based on direct observation of the spin moment via Compton scattering and a comparison with literature magnetization data 11 .…”

Section: Discussionmentioning

confidence: 99%

Quantitative analysis of magnetic spin and orbital moments from an oxidized iron (1 1 0) surface using electron magnetic circular dichroism

Thersleff

Rusz

Rubino

et al. 2015

Sci Rep

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Understanding the ramifications of reduced crystalline symmetry on magnetic behavior is a critical step in improving our understanding of nanoscale and interfacial magnetism. However, investigations of such effects are often controversial largely due to the challenges inherent in directly correlating nanoscale stoichiometry and structure to magnetic behavior. Here, we describe how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic Circular Dichroism (EMCD) signals as a function of scattering angle to locally probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0) surface. Experiments and simulations both reveal a strong dependence of the magnetic orbital to spin ratio on its scattering vector in reciprocal space. We exploit this variation to extract the magnetic properties of the oxide cladding layer, showing that it locally may exhibit an enhanced orbital to spin moment ratio. This finding is supported here by both spatially and angularly resolved EMCD measurements, opening up the way for compelling investigations into how magnetic properties are affected by nanoscale features.

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“…Thus, the direct deposition of Au atoms onto the IO NPs must be performed in organic phase. 22, 29, 60–65 For example, Wang et al synthesized IO-Au core-shell NPs by heating a mixture of OA-capped Fe 3 O 4 NPs, Au acetate (Au(OOCCH 3 ) 3 ) and 1,2-hexadecanediol in phenyl ether to 180–190°C for 1.5 h. 60 Xu et al coated Au onto OA- and OAM-capped IO NPs at room temperature by gently reducing HAuCl 4 in a chloroform solution containing OAM. 62 OAM served as a mild reducing agent as well as a surfactant.…”

Section: Synthesismentioning

confidence: 99%

Synthesis and properties of magnetic-optical core–shell nanoparticles

et al. 2017

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Due to their high integrity, facile surface chemistry, excellent stability, and dual properties from the core and shell materials, magnetic-plasmonic core-shell nanoparticles are of great interest across a number of science, engineering and biomedical disciplines. They are promising for applications in a broad range of areas including catalysis, energy conversion, biological separation, medical imaging, disease detection and treatment. The technological applications have driven the need for high quality nanoparticles with well controlled magnetic and optical properties. Tremendous progress has been made during past few decades in synthesizing and characterizing magnetic-plasmonic core-shell nanoparticles, mainly iron oxide-gold core-shell nanoparticles. This review introduces various approaches for the synthesis of spherical and anisotropic magnetic-plasmonic core-shell nanoparticles focusing on iron oxide-gold core-shell nanoparticles. Growth mechanisms are discussed to provide understanding of the key factors controlling shape-controlled synthesis. Magnetic and optical properties are summarized from both computational and experimental studies.

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Magnetism of iron oxide based core-shell nanoparticles from interface mixing with enhanced spin-orbit coupling

Cited by 52 publications

References 41 publications

Examination of the magnetism dynamics from intermixing effects in γ-Fe2O3/MnO core-shell nanoparticles

Examination of the magnetism dynamics from intermixing effects in γ-Fe2O3/MnO core-shell nanoparticles

Quantitative analysis of magnetic spin and orbital moments from an oxidized iron (1 1 0) surface using electron magnetic circular dichroism

Synthesis and properties of magnetic-optical core–shell nanoparticles

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