Abstract
The magnetic properties of nanoparticles are investigated by x-ray magnetic circular dichroism. Sum rules relating the orbital and spin moment in the band to the absorption cross sections show that the Fe orbital moment is considerably high, explaining the origin of the large coercivity of this material at room temperature. Moreover, at , the collapse of the coercivity and the magnetocrystalline anisotropy coincides with a strong reduction of the spin-orbit coupling evidenced by a drastic drop of . The decrease in originates from changes in the electron transfer between Fe and O ions accompanied by significant modifications of some of the Fe-O bond distances. Similarly, the recovery of at lower temperatures mimics the behavior of the Fe-O bond lengths.
1 More- Received 13 November 2008
DOI:https://doi.org/10.1103/PhysRevB.79.094404
©2009 American Physical Society