Spin canting and size effects in nanoparticles of nonstoichiometric cobaltferrite

The magnetic properties of nonstoichiometric cobalt ferrite nanocrystals di ffering by their sizes were investigated by magnetic measurements and Fe-57 Mossbauer spectroscopy. We found that the spin-wave Bloch exponent increas es with increasing particle size, in agreement with previous studies. Under a magnetic field of 7 T, we observed that the partial reorientation of the two ferrimagnetic Fe3+ sublattice magnetizations towards the field directi on increases with increasing the particle size; we discuss the applicabilit y of an intrinsic spin canting model as a function of the particle size. An evaluation of the relative amounts of cobalt and iron in each spinel site is given. (C) 2001 American Institute of Physics.