Exchange-spring behavior in nanopowders of CoFe2O4–CoFe2

J. M. Soares, F. A. O. Cabral, J. H. de Araújo, F. L. A. Machado
2011 Applied Physics Letters  
The nature of the magnetic interactions among core-shell nanoparticles of CoFe 2 O 4 -CoFe 2 having an average particle size of 32 nm were investigated by ␦m plots. It was found that the interactions are mainly demagnetizing in nature for nanoparticles with core diameters larger than 26 nm. For smaller values of core diameters, the exchange-spring phenomenon takes place due to the exchange-coupling at the core-shell interface. The critical thickness of the shell was estimated to be 7.8 nm. The
more » ... verall results are in excellent agreement with current theoretical models.
doi:10.1063/1.3552677 fatcat:pjcqipngxbc3jh4qo4l36ux2bu