Magnetism of FePt Nanoclusters in Polyimide

Mircea Chipara, Tom George, Yingfan Xu, Ralph Skomski, Lanping Yue, Nasar Ali, David J. Sellmyer

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Abstract

FePt nanoclusters have been implanted onto polyimide films and subjected to thermal annealing in order to obtain a special magnetic phase (L10) dispersed within the polymer. SQUID measurements quantified the magnetic features of the as-prepared and annealed hybrid films. As-implanted FePt nanoparticles in polyimide films exhibited a blocking temperature of 70 ± 5 K. Thermal annealing in zero and 10 kOe applied magnetic field increased the magnetic anisotropy and coercivity of the samples. Wide Angle X-Ray Scattering confirmed the presence of FePt and L10 phase. All samples (as deposited and annealed) exhibited electron spin resonance spectra consisting of two overlapping lines. The broad line was a ferromagnetic resonance originating from FePt nanoparticles. Its angular dependence indicated the magnetic anisotropy of FePt nanoparticles. SEM micrographs suggest a negligible coalescence of FePt nanoparticles, supporting that the enhancement of the magnetic properties is a consequence of the improvement of the L10 structure. The narrow ESR line was assigned to nonmagnetic (paramagnetic) impurities within the samples consistent with graphite-like structures generated by the local degradation of the polymer during implantation and annealing. Raman spectroscopy confirmed the formation of graphitic structures in annealed KHN and in KHN-FePt.

Original languageEnglish (US)
Article number587847
JournalJournal of Nanomaterials
Volume2015
DOIs
Publication statusPublished - Jan 1 2015

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ASJC Scopus subject areas

  • Materials Science(all)

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Chipara, M., George, T., Xu, Y., Skomski, R., Yue, L., Ali, N., & Sellmyer, D. J. (2015). Magnetism of FePt Nanoclusters in Polyimide. Journal of Nanomaterials, 2015, [587847]. https://doi.org/10.1155/2015/587847