Ferromagnetism induced by hybridization of Fe 3d orbitals with ligand InSb bands in n-type ferromagnetic semiconductor (In,Fe)Sb

TL;DR

This study investigates the electronic and magnetic properties of Fe-doped (In,Fe)Sb, revealing that ferromagnetism arises from hybridization of Fe 3d orbitals with InSb bands, which explains its high Curie temperature.

Contribution

The paper provides experimental evidence that ferromagnetism in (In,Fe)Sb is due to Fe 3d orbital hybridization with host bands, clarifying the mechanism behind its high Curie temperature.

Findings

Fe ions have an intermediate valence state between Fe3+ and Fe2+.

Ferromagnetism is linked to Fe 3d and InSb band hybridization.

Magnetic circular dichroism correlates with net magnetization.

Abstract

Fe-doped III-V ferromagnetic semiconductor (FMS) (In,Fe)Sb is a promising material for spintronic device applications because of the n-type carrier conduction and the ferromagnetism with high Curie temperature (TC > 300 K). To clarify the mechanism of the high-TC ferromagnetism, we have investigated the electronic structure and magnetic properties of an (In,Fe)Sb thin film by performing x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at the Fe L2,3 edges. The magnetic-field dependence of the XMCD spectra reveals that there are ferromagnetic-like Fe and paramagnetic-like Fe components in the (In,Fe)Sb thin film. The XAS and XMCD spectra of the ferromagnetic-like and paramagnetic-like Fe components resemble those of other Fe-doped FMSs and extrinsic oxides, respectively. The finite value of the ratio between the orbital and spin magnetic moments estimated by applying the XMCD sum rules indicates that the valence state of the Fe ions substituting for the In sites in (In,Fe)Sb is not purely ionic Fe3+, but intermediate between Fe3+ and Fe2+. The qualitative correspondence between the magnetic-field dependence of the visible-light magnetic circular dichroism intensity and that of the XMCD intensity demonstrates that the Zeeman splitting of the InSb band is proportional to the net magnetization of the doped Fe. These results suggest that the ferromagnetism of (In,Fe)Sb originates from the Fe 3d orbitals hybridized with the host InSb bands.