On the first evidence of exchange-bias feature in magnetically contrasted consolidates made from CoFe2O4-CoO core-shell nanoparticles

• Published in: Scientific reports 2019-12, Vol.9 (1), p.1-11, Article 19468
• Main Authors: Flores-Martinez, Nancy, Franceschin, Giulia, Gaudisson, Thomas, Haj-Khlifa, Sonia, Derouich, Sarra Gam, Yaacoub, Nader, Grenèche, Jean-Marc, Menguy, Nicolas, Valenzuela, Raul, Ammar, Souad
• Format: Article
• Language: English
• Subjects: 639/301/119/997; 639/925/357/997; Cobalt; Condensed Matter; Electron microscopy; Humanities and Social Sciences; Magnetic fields; Magnetism; multidisciplinary; Nanoparticles; Oxides; Physics; Plasma sintering; Science; Science (multidisciplinary); Spectrometry; X-ray diffraction
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-55649-y

Hetero-nanostructures based on magnetic contrast oxides have been prepared as highly dense nanoconsolidates. Cobalt ferrite-cobalt oxide core-shell type nanoparticles (NPs) were synthesized by seed mediated growth in polyol and subsequently consolidated by Spark Plasma Sintering (SPS) at 500 °C for a few minutes while applying a uniaxial pressure of 100 MPa. It is interesting to note that the exchange bias feature observed in the core-shell NPs is reproduced in their ceramic counterparts, or even attenuated. A systematic structural characterization was then carried out to elucidate the decrease in the exchange magnetic field, involving mainly advanced X-ray diffraction, zero-field and in-field 57 Fe Mössbauer spectrometry, magnetic measurements and electron microscopy.