Exchange bias and magnetocrystalline anisotropy of non-stoichiometric CoxFe3−xO4 nanoparticles

• Published in: Journal of materials science. Materials in electronics 2022-04, Vol.33 (12), p.9629-9640
• Main Authors: Gokul, B., Matheswaran, P., Pandian, M., Arun Paul, C., Ravikumar, K., Abd El-Rehim, A. F.
• Format: Article
• Language: English
• Subjects: Anisotropy; Bias; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cobalt; Coercivity; Exchanging; Iron oxides; Magnetic properties; Materials Science; Nanoparticles; Optical and Electronic Materials; Photoelectrons; Room temperature; Stoichiometry; X ray photoelectron spectroscopy
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-021-07606-7

We report the influence of Co concentration on the exchange bias and magnetocrystalline anisotropy of Co x Fe 3− x O 4 ( x  = 0.0, 0.4, 0.7, 1.0) nanoparticles. Co ions were substituted in magnetite (Fe 3 O 4 ) nanoparticles to obtain non-stoichiometric Co x Fe 3− x O 4 nanoparticles. The concentration of Co (mol) was varied from 0.0 to 1.0. Structure and magnetic anisotropic properties of non-stoichiometric Co x Fe 3− x O 4 nanoparticles were studied. The prepared Co x Fe 3− x O 4 nanoparticle was quasi-spherical in shape with particle sizes ranging from 15 to 20 nm. Raman and X-ray photoelectron spectroscopic (XPS) studies suggest the transformation of inverse to normal spinel structure concerning Co concentration. Blocking temperature increases from 155 to 302 K with an increase in concentration (mol) from 0.0 to 1.0 respectively. Co x Fe 3− x O 4 ( x  = 0.7) resulted in an exchange bias field and large magnetocrystalline anisotropy of about 70 Oe and 5.38 × 10 4  J/m 3 . Due to large magnetocrystalline anisotropy, Co x Fe 3− x O 4 ( x  = 0.7) shows a low exchange bias field. Co x Fe 3− x O 4 ( x  = 1.0) show room temperature hysteresis with coercivity of about 14.5 kOe at 5 K and M S of 45 emu/g.