Title
Line Narrowing in Mössbauer Spectra of Superparamagnetic Fe3O4 Nanoparticles.
Department
Department of Chemistry
Document Type
Article
Publication Date
11-24-2014
Abstract
Nanoparticles of magnetic crystals below a critical size are single domain and exhibit superparamagnetism. If there are N atoms or molecules with magnetic moment μ in each particle, the magnetic moment of the particle is Nν. At high temperatures the thermal fluctuations of the magnetic moments give an ensemble average moment of zero and the Mössbauer spectrum is a single line. As the temperature, T, is lowered the fluctuations slow down and the sample acquires a magnetization and the Mossbauer line broadens and eventually shows magnetic hyperfine splitting. We have observed 57Fe line broadening in nanoparticles of ferrimagnetic Fe3O4 with diameters of 5.3 and 10.6 nm. The results have been analyzed using the motional narrowing equation familiar in nuclear magnetic resonance to determine the superparamagnetic fluctuation time and magnetic anisotropy.
Recommended Citation
Hah, H. Y.; Gray, S.; johnson, C. E.; Johnson, J. A.; Kolesnichenko, V.; Kucheryavy, P.; and Goloverda, G., "Line Narrowing in Mössbauer Spectra of Superparamagnetic Fe3O4 Nanoparticles." (2014). Faculty and Staff Publications. 105.
https://digitalcommons.xula.edu/fac_pub/105
Comments
DOI: 10.1088/1742-6596/548/1/012021
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