X-ray absorption and magnetic circular dichroism characterization of Mo1-xFexO2 (x=0-0.05) thin films grown by pulsed laser ablation

Abstract

The electronic and magnetic properties of well characterized Mo1-xFexO2 (x=0-0.5) thin films that show ferromagnetism at room temperature (RT) have been investigated by the means of near edge x-ray absorption fine structure (NEXAFS) and x-ray magnetic circular dichroism (XMCD) experiments at the O K-, Fe L-, and Mo M-edges. The NEXAFS spectra at O K-and Mo M-3,M-2-edges show a strong hybridization of O 2p-4d Mo orbitals, and Mo ions change their symmetry with the substitution of Fe ions into MoO2 matrix. The Fe 2p NEXAFS/XMCD spectra exhibit multiple absorption peaks and an appreciable XMCD signal that persists even at RT. These results demonstrate that Fe is in a mixed valence state of Fe2+-Fe3+, substituting at the Mo site and that the Fe2+/3+ ions are ferromagnetically polarized.