Spin rotation in alpha-Fe2O3 nanoparticles by interparticle interactions

摘要

Nanoparticles of alpha-Fe2O3 (hematite) typically have the sublattice magnetization directions in the hexagonal (001) plane below the Neel temperature. By use of Mossbauer spectroscopy we have found that for agglomerated particles the sublattice magnetization may be rotated of the order of 15degrees out of plane, depending on the particle size. The spin rotation can be explained by exchange interaction between neighboring particles with nonparallel (001) planes. The results imply that interparticle interactions can lead to spin directions deviating from the easy axis defined by the magnetic anisotropy.