Pure dipolar-interacted CoFe{sub 2}O{sub 4} nanoparticles and their magnetic properties
- Anhui Key Laboratory of Information Materials and Devices, School of Physics and Materials Science, Anhui University, Hefei 230039 (China)
Graphical abstract: The mono-dispersed CoFe{sub 2}O{sub 4} nanoparticles with the uniform size of 10.5 ± 2 nm were first synthesized and then they were embedded in amorphous SiO{sub 2} matrix with different CoFe{sub 2}O{sub 4} nanoparticles’ concentrations. The large coercivity (3056 Oe) and the remanence ratio (0.63) were obtained by suitably diluting CoFe{sub 2}O{sub 4} nanoparticles into the SiO{sub 2} matrix. The reciprocal of the absolute maximum of δm and the M{sub r}/M{sub s} ratio behave in the same trend (as shown in (e)), indicating that the M{sub r}/M{sub s} ratio was dominated by the interparticle dipolar interaction. The present work is meaningful for revealing the underlying mechanism in nano-scaled magnetic system and improving the magnetic performance. - Highlights: • The mono-dispersed CoFe{sub 2}O{sub 4} nanoparticles with the uniform size of 10.5 ± 2 nm were synthesized by the thermal decomposition of metals acetylacetonates in solvents with high boiling point. • The large coercivity (3056 Oe) and the remanence ratio (0.63) were obtained by diluting CoFe{sub 2}O{sub 4} nanoparticles into the SiO{sub 2} matrix with a suitable concentration. • The surface anisotropy and interparticle dipolar interaction affect the magnetic performance and magnetic ordering state. • It was observed that the M{sub r}/M{sub s} ratio was dominated by the interparticle dipolar interaction. - Abstract: The mono-dispersed and uniform CoFe{sub 2}O{sub 4} nanoparticles were synthesized by the thermal decomposition of Fe(acac){sub 3} and Co(acac){sub 2}. Then the CoFe{sub 2}O{sub 4} nanoparticles were diluted in amorphous SiO{sub 2} matrix with different CoFe{sub 2}O{sub 4} nanoparticles’ concentrations. All samples show the positive or negative exchange bias behavior, indicating the presence of canted spin layer at the CoFe{sub 2}O{sub 4} nanoparticles’ surface. The large effective anisotropy constant (3.38 × 10{sup 6} erg/cm{sup 3}) was observed, which can be attributed to the induced surface anisotropy by the canted surface spins. The reduced magnetization (M{sub r}/M{sub s}) was dominated by the interparticle dipolar interaction while the coercivity (H{sub c}) was determined by the synergistic effects of the surface anisotropy, interparticle dipolar interaction and interface effect. By suitably diluting CoFe{sub 2}O{sub 4} in the SiO{sub 2} matrix, the high H{sub c} (3056 Oe) and the M{sub r}/M{sub s} (0.63) can be obtained, which is larger than most of those reported before. The present work is meaningful for revealing the underlying mechanism in nano-scaled magnetic system and improving the magnetic performance.
- OSTI ID:
- 22420809
- Journal Information:
- Materials Research Bulletin, Vol. 62; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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