INVESTIGATION OF THE OXIDE SURFACE-LAYER ON FINE IRON PARTICLES

The spin pinning in the oxide surface layer has been observed directly , and it is considered a possible reason why the oxide layer leads to the decrease of the specific saturation magnetization for fine iron pa rticles. The pinning depth has been estimated by means of a Mossbauer effect under an applied field of 6 T in a thermal-cycle process. The D ebye temperature of the oxide layer and the temperature dependence of f2/f1 have been obtained, where f1 and f2 are the Mossbauer recoilless fractions for the inner alpha-Fe core and the oxide layer, respective ly. Furthermore, the estimation for the thickness of an oxide layer ha s been improved.