Spin and orbital magnetic moments of Fe in the n -type ferromagnetic semiconductor (In,Fe)As

The electronic and magnetic properties of Fe atoms in the ferromagnetic semiconductor (In,Fe)As codoped with Be have been studied by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) at the Fe L2,3 edge. The XAS and XMCD spectra showed simple spectral line shapes similar to Fe metal, but the ratio of the orbital and spin magnetic moments (Morb/Mspin) estimated using the XMCD sum rules was significantly larger than that of Fe metal, indicating a significant orbital moment of Fe 3d electrons in (In,Fe)As:Be. The positive value of Morb/Mspin implies that the Fe 3d shell is more than half-filled, which arises from the hybridization of the Fe3+ (d5) state with the charge-transfer d6L¯ states, where L¯ is a ligand hole in the host valence band. The XMCD intensity as a function of magnetic field indicated hysteretic behavior of the superparamagnetic-like component due to discrete ferromagnetic domains.