Inversed tunneling magnetoresistance in hybrid FePt/Fe3 O 4 core/shell nanoparticles systems

Yunpeng Zhang*, Hui Xing, Narayan Poudyal, Vikas Nandwana, Chuan Bing Rong, Shi Shen Yan, Hao Zeng, J. P. Liu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Magnetotransport studies were performed on hybrid FePt/ Fe3 O4 core/shell nanoparticle systems. The linear relationship of LnR versus T-1/2 with and without a magnetic field confirms the physical picture of thermally assisted interparticle tunneling. A sign inversion of tunneling magnetoresistance (TMR) from negative to positive with decreasing temperature was observed. In the high temperature region, the core/shell nanoparticles show negative TMR similar to that of Fe3 O4 nanoparticles. The magnitude of the TMR in the FePt/ Fe3 O 4 core/shell nanoparticle systems is smaller than that in Fe 3 O4 nanoparticle systems, likely due to lower spin polarization of conducting electrons in FePt. However the MR becomes positive in the low temperature region. We propose that this behavior originates from the resonance tunneling between the FePt cores via the defect states near the Fermi level in the Fe3 O4 shells which dominates the magnetotransport of the FePt/ Fe3 O4 nanoparticle system at low temperatures.

Original languageEnglish (US)
Article number103905
JournalJournal of Applied Physics
Issue number10
StatePublished - Nov 15 2010
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy


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