Room Temperature High coercivity CoFe2O4 nanoparticles
Mukta V. Limaye1, Shashi B. Singh1, S. K. Date1 and Sulabha K. Kulkarni1
1
DST unit on nanoscience, Department of Physics, University of Pune, Pune-411007, India
Correspondence should be addressed to mukta@physics.unipune.ernet.in
ABSTRACT
A very high coercivity (9.47 kOe) has been obtained for 20 nm size CoFe2O4
nanoparticles, chemically synthesized and capped with oleic acid. X-ray diffraction
analysis confirms the formation of spinel phase of CoFe2O4 nanoparticles. All attempts
so far to obtain high coercivity at room temperature have lead to highest coercivity of 5.3
kOe for CoFe2O4 particles prepared by chemical route [1] and 9.3 kOe for thin films thin
films deposited on SiO2 single crystal substrate. [2] To the best of authors’ knowledge
this is the first report on the high coercivity CoFe2O4 nanoparticles at room temperature.
The sample is annealed at different temperatures and their magnetic properties are
studied. The Mössbauer spectroscopic studies revealed that organic capping molecules
exhibit very important role. The high coercivity is observed due to strong electric dipolar
interactions between the particles, steric hindrance produced by capping molecules and
magnetocrystalline anisotropy.
References
1. Y. C. Wang, J. Ding, J. B. Yi, B. H. Liu, T. Yu, Z. X. Shen, Appl. Phys. Lett. 84,
2596 (2004)
2. B.H. Liu, J. Ding, Z.L. Dong, C. B. Bothroyd, J.H. Yin, J. B. Yi, Phys. Rev. B 74,
184427 (2006)