Effect of nanosizing on lattice and magnon modes of hematite

Broadening of Raman lines and a decrease of frequencies relative to the bulk material are observed for the lattice modes of nanoparticles of the hematite phase of Fe2O3. The magnon mode frequency is observed to shift up with reduced particle size in contrast to the lattice modes. The effects are suggested to be a result of phonon confinement and represent the first observation of phonon confinement effects on magnon modes. The Fe2O3 nanoparticles are produced by laser decomposition of Fe3O4 nanoparticles. X-ray diffraction and Raman frequency shifts indicate the Fe2O3 nanoparticles are smaller than the parent Fe3O4 nanoparticles.