Spin collinearity and thermal disorder in ε-Fe2O3

Studies of magnetoelectric ε-Fe2O3 nanoparticles (30nm) in silica by Fe57 Mössbauer spectrometry (4.2–600K,0–6T) are reported. They indicate a magnetic/structural transition at ∼130K, a high-temperature collinear ferrimagnetic spin structure similar to FeGaO3 and FeAlO3, and the Curie temperature TC at 585K. Reduced hyperfine field versus T∕TC is (S=5∕2) Brillouin-like or Langevin-like according to the structural site. The magnetization at 300K is estimated to 0.25μB∕Fe in accord with published data.