Effect of oxide layer on the hysteresis behavior of fine Fe particles

The effects of surface oxidation on the structural and magnetic properties of fine Fe particles prepared by the evaporation technique have been studied using transmission electron microscopy, x-ray photoelectron spectroscopy, superconducting quantum interference device magnetometry, and Mössbauer spectroscopy. By varying the argon pressure, particles were obtained with sizes in the range of 60–350 Å. The hysteresis behavior was found to be strongly dependent on the variation in the amount of surface oxidation. The differences in the magnetic behavior due to variation in size and oxidation have been explained by considering a shell/core model for the particle morphology with the shell consisting of Fe oxides surrounding the α-Fe core.