Enhanced tunneling magnetoresistance and high-spin polarization at room temperature in a polystyrene-coated Fe3O4 granular system


W. Wang, M. Yu, M. Batzill, J. He, U. Diebold, J. Tang

Department of Physics, University of New Orleans, New Orleans, Louisiana 70118, U.S.A.
Advanced Materials Research Institute, University of New Orleans, New Orleans, Louisiana 70148, U.S.A.
Department of Physics, Tulane University, New Orleans, Louisiana 70118, U.S.A.
Coordinated Instrumentation Facility, Tulane University, New Orleans, Louisiana 70118, U.S.A.

Phys. Rev. B 73 (2006) 134412

Polystyrene-coated Fe3O4 nanoparticles through surface engineering exhibit an intergranular tunneling magnetoresistance (MR) ratio of 22.8% at room temperature and a maximum MR of 40.9% at 110 K. The drastic enhancement of the MR ratio clearly suggests that there is high degree of spin polarization even at room temperature for half metallic Fe3O4. The estimated spin polarization P is about 54% and 83% at room temperature and 110 K, respectively.

Reprints available from U. Diebold (diebold at iap_tuwien_ac_at).

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