Spin canting and size effects in nanoparticles of nonstoichiometric cobalt ferrite

The magnetic properties of nonstoichiometric cobalt ferrite nanocrystals differing by their sizes were investigated by magnetic measurements and Fe57 Mössbauer spectroscopy. We found that the spin-wave Bloch exponent increases 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 direction increases with increasing the particle size; we discuss the applicability 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.