Inter-particle spin-polarized tunneling in arrays of magnetite nanocrystals

Inter-particle spin-polarized tunneling was measured in an organically capped magnetite nanocrystal (NC) array deposited between 30 nm spaced gold electrodes. Magnetoresistance (MR) measurements performed around the blocking temperature ( T b ) of the magnetic moments of the particles in the array,...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2009-07, Vol.321 (13), p.1933-1938
Main Authors: Taub, Nurit, Tsukernik, Alexander, Markovich, Gil
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Electronic transport in condensed matter
Exact sciences and technology
Magnetite nanocrystals
Physics
Spin polarized transport
Superparamagnetism
Tunneling magnetoresistance
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Summary:Inter-particle spin-polarized tunneling was measured in an organically capped magnetite nanocrystal (NC) array deposited between 30 nm spaced gold electrodes. Magnetoresistance (MR) measurements performed around the blocking temperature ( T b ) of the magnetic moments of the particles in the array, which was relatively high (220 K), yielded negative MR values of the order of 10–25% under moderate magnetic fields of several kOe. The field dependence of the MR followed closely the square of the film's magnetization and its voltage dependence indicated maximal spin polarization around the Fermi level. These findings suggested that the measured MR is the result of spin-polarized tunneling between individual magnetite NCs acting as superparamagnetic spin polarizers.
ISSN:0304-8853
DOI:10.1016/j.jmmm.2008.12.012