We have studied the coexistence of exchange bias (EB) effect and spin-dependent magnetotransport in a Ni/NiO nanogranular sample by measuring the magnetization (M) and the magnetoresistance (MR) versus the magnetic field (H) in the 5-250 K temperature (T) range, both in zero-field-cooling (ZFC) and field-cooling (FC) conditions. The sample consisted of Ni nanocrystallites (mean size ∼13 nm) dispersed in a NiO matrix; the Ni volume fraction was ∼33, above the percolation threshold for electrical conductivity, as revealed by the low resistivity (order of 10-3 ωm) and by its growth with increasing T. The EB and magnetotransport phenomena appear strictly intertwined: the FC M(H) and MR(H) loops exhibit a similar horizontal shift, corresponding to an exchange field of ∼460 Oe at T = 5 K, which decreases with increasing T and disappears at ∼200 K. Both the EB and the magnetotransport properties have been explained, considering the presence of a structurally disordered component of the NiO matrix around the Ni nanocrystallites, whose spin-glass-like magnetic character rules the interface exchange interaction with the Ni phase and the spin-dependent conductivity. © 2011 American Institute of Physics.

Coexistence of exchange bias effect and giant magnetoresistance in a Ni/NiO nanogranular sample

DEL BIANCO, Lucia
Primo
;
SPIZZO, Federico
Secondo
;
TAMISARI, Melissa
Penultimo
;
2011

Abstract

We have studied the coexistence of exchange bias (EB) effect and spin-dependent magnetotransport in a Ni/NiO nanogranular sample by measuring the magnetization (M) and the magnetoresistance (MR) versus the magnetic field (H) in the 5-250 K temperature (T) range, both in zero-field-cooling (ZFC) and field-cooling (FC) conditions. The sample consisted of Ni nanocrystallites (mean size ∼13 nm) dispersed in a NiO matrix; the Ni volume fraction was ∼33, above the percolation threshold for electrical conductivity, as revealed by the low resistivity (order of 10-3 ωm) and by its growth with increasing T. The EB and magnetotransport phenomena appear strictly intertwined: the FC M(H) and MR(H) loops exhibit a similar horizontal shift, corresponding to an exchange field of ∼460 Oe at T = 5 K, which decreases with increasing T and disappears at ∼200 K. Both the EB and the magnetotransport properties have been explained, considering the presence of a structurally disordered component of the NiO matrix around the Ni nanocrystallites, whose spin-glass-like magnetic character rules the interface exchange interaction with the Ni phase and the spin-dependent conductivity. © 2011 American Institute of Physics.
DEL BIANCO, Lucia; Spizzo, Federico; Tamisari, Melissa; A., Castiglioni
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11392/1624466
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