Abstract
Effect of surface spins in chromium oxide (Cr2O3) coated maghemite (γ-Fe2O3) nanoparticles (13 nm) as prepared by microwave plasma technique have been studied in detail. The temperature dependent zero field cooled/field cooled (ZFC/FC) measurements revealed the blocking temperature at TB = 75 K. Simulated ZFC/FC curves exhibited large value of effective anisotropy of Cr2O3 coated γ-Fe2O3 nanoparticles as compared to bulk γ-Fe2O3 but less than bare γ-Fe2O3 nanoparticles. Bloch's law was fitted on MS-T data and revealed the values of Bloch's constant B = 3.523 × 10−4 K−b and Bloch's exponent b = 1.10. The higher value of B than in bulk is due to weaker exchange coupling J (B ̴ 1/J) on the surface of nanoparticle due to disorder surface spins, while lower value of b is due to no spin wave excitation in presence of large energy band gap at nanoscale. Kneller's law fit on HC-T data deviated in all temperature range which is due to strong surface anisotropy, core-shell interactions and superparamagnetism. Interparticle interactions and spin glass behavior were investigated by using different physical laws for f-dependent ac susceptibility and they confirmed the presence of spin glass behavior which is due to disordered frozen surface spins and random interparticle interactions.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
