Local electronic states of Fe4N films revealed by x-ray absorption spectroscopy and x-ray magnetic circular dichroism

Abstract

We performed x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at Fe L2,3 and N K-edges for Fe4N epitaxial films grown by molecular beam epitaxy. In order to clarify the element specific local electronic structure of Fe4N, we compared experimentally obtained XAS and XMCD spectra with those simulated by a combination of a first-principles calculation and Fermi's golden rule. We revealed that the shoulders observed at Fe L2,3-edges in the XAS and XMCD spectra were due to the electric dipole transition from the Fe 2p core-level to the hybridization state generated by σ* anti-bonding between the orbitals of N 2p at the body-centered site and Fe 3d on the face-centered (II) sites. Thus, the observed shoulders were attributed to the local electronic structure of Fe atoms at II sites. As to the N K-edge, the line shape of the obtained spectra was explained by the dipole transition from the N 1s core-level to the hybridization state formed by π* and σ* anti-bondings between the Fe 3d and N 2p orbitals. This hybridization plays an important role in featuring the electronic structures and physical properties of Fe4N.