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Tunnel magnetoresistance of thin‐film nanogranular metal–dielectric composites ( x )Ni–(1− x )PNBZT
Author(s) -
Kalgin A. V.,
Gridnev S. A.,
Gribe Z. H.,
Kashirin M. A.
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201552060
Subject(s) - magnetoresistance , materials science , dielectric , percolation threshold , condensed matter physics , amorphous solid , composite material , ferromagnetism , thin film , tunnel magnetoresistance , percolation (cognitive psychology) , magnetic field , electrical resistivity and conductivity , layer (electronics) , crystallography , chemistry , nanotechnology , neuroscience , biology , physics , optoelectronics , engineering , quantum mechanics , electrical engineering
Thin‐film nanogranular metal–dielectric composites ( x )Ni–(1− x )[Pb 0.81 Sr 0.04 (Na 0.5 Bi 0.5 ) 0.15 ][(Zr 0.575 Ti 0.425 )]O 3 (denoted as ( x )Ni–(1− x )PNBZT) were prepared by the ion‐beam sputtering method. The X‐ray diffraction analysis has revealed the presence of two phases in the composites: a crystalline Ni phase and an amorphous PNBZT phase. Composites ( x )Ni–(1− x )PNBZT with compositions below the percolation threshold manifest a negative magnetoresistance, whose highest values of 0.13% at 287 K and 0.78% at 77 K are observed near the percolation threshold at х с = 35 at.% for a composite sample of 0.31Ni–0.69PNBZT placed in a constant magnetic field with the strength of 8000 Oe. The magnetoresistance of the composites ( x )Ni–(1− x )PNBZT is increased with the growth of the constant magnetic field strength, and the dependence remains the same as a polarity of the magnetic field is varied. The charge transport in the composites ( x )Ni–(1− x )PNBZT over a temperature interval of 188–287 K is shown to be attributed to the inelastic resonant tunneling of electrons through energy barriers in a dielectric layer of PNBZT between crystalline ferromagnetic nanogranules of Ni. Therefore, to explain the experimentally established regularities of the negative magnetoresistance, the tunnel magnetoresistance model has been used.