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 similar to 13 nm) dispersed in a NiO matrix; the Ni volume fraction was similar to 33%, above the percolation threshold for electrical conductivity, as revealed by the low resistivity (order of 10(-3) Ohm m) 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 similar to 460 Oe at T = 5 K, which decreases with increasing T and disappears at similar to 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.

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

DEL BIANCO, LUCIA;
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 similar to 13 nm) dispersed in a NiO matrix; the Ni volume fraction was similar to 33%, above the percolation threshold for electrical conductivity, as revealed by the low resistivity (order of 10(-3) Ohm m) 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 similar to 460 Oe at T = 5 K, which decreases with increasing T and disappears at similar to 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.
L. Del Bianco; F. Spizzo; M. Tamisari; A. Castiglioni
File in questo prodotto:
Eventuali allegati, non sono esposti

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/105328
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 10
  • ???jsp.display-item.citation.isi??? 9
social impact