Examination of the magnetism dynamics from intermixing effects in γ-Fe{sub 2}O{sub 3}/MnO core-shell nanoparticles

Journal Article · Thu May 07 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4915096· OSTI ID:22409927

Su, T. T.; Ouyang, H. ^[1]; Freeland, J. W. ^[2]

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1. Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China)
2. Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

We have examined the effects of core-shell intermixing on the dynamical magnetism of γ-Fe{sub 2}O{sub 3}/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-Fe{sub 2}O{sub 3}/MnO relative to the γ-Fe{sub 2}O{sub 3} 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-Fe{sub 2}O{sub 3} core. Our results show that both the MnO shell and the interfacial intermixed layer are important in determining the core-shell nanoparticle magnetism.

• OSTI ID: 22409927
• Journal Information: Journal of Applied Physics, Vol. 117, Issue 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
77 NANOSCIENCE AND NANOTECHNOLOGY
ABSORPTION SPECTROSCOPY
FERRITES
INTERFACES
IRON
IRON OXIDES
LAYERS
MAGNETISM
MANGANESE
MANGANESE IONS
MANGANESE OXIDES
MOESSBAUER EFFECT
NANOPARTICLES
RELAXATION
SURFACES
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY