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      https://www.ias.ac.in/article/fulltext/pram/065/04/0739-0743

    • Keywords

       

      Superparamagnetism; Monte Carlo; sol-gel; anisotropy; nanocomposites

    • Abstract

       

      The interaction effects in magnetic nanoparticle system were studied through a Monte Carlo simulation. The results of simulations were compared with two different magnetic systems, namely, iron oxide polymer nanocomposites prepared by polymerization over core and nanocrystalline cobalt ferrite thin films prepared by sol-gel process. The size of the particles in the nanocomposites were estimated to be ∼15 nm with very little agglomeration. The low values of the coercivity obtained from the hysteresis measurements performed confirm that the system is superparamagnetic. SEM studies showed the cobalt ferrite films to have a nanocrystalline character, with particle sizes in the nanometer range. Hysteresis measurements performed on the thin films coated on silicon do not give evidence of the superparamagnetic transition up to room temperature and the coercivity is found to increase with decreasing film thickness. Comparison with simulations indicate that the nanocomposites behave like a strongly interacting array where exchange interactions lead to high blocking temperatures, whereas the films are representative of a semi-infinite array of magnetic clusters with weak interactions and thickness-dependent magnetic properties.

    • Author Affiliations

       

      Raksha Sharma1 C Pratima2 Subhalakshmi Lamba3 S Annapoorni1

      1. Department of Physics and Astrophysics, University of Delhi, Delhi - 110 007, India
      2. Department of Physics, Allahabad University, Allahabad - 211 002, India
      3. National Physical Laboratory, Dr. K. S. Krishnan Marg, Delhi - 110 012, India
    • Dates

       
  • Pramana – Journal of Physics | News

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