Electronic Structure of the Ferromagnetic Semiconductor Fe-doped Ge Revealed by Soft X-ray Angle-Resolved Photoemission Spectroscopy

Abstract

Ge${}_{1-x}$Fe${}_x$ (Ge:Fe) shows ferromagnetic behavior up to a relatively high temperature of 210 K, and hence is a promising material for spintronic applications compatible with Si technology. We have studied its electronic structure by soft x-ray angle-resolved photoemission spectroscopy (SX-ARPES) measurements in order to elucidate the mechanism of the ferromagnetism. We observed finite Fe 3$d$ components in the states at the Fermi level ($E_F$) in a wide region in momentum space and $E_F$ was located above the valence-band maximum (VBM). First-principles supercell calculation also suggested that the $E_F$ is located above the VBM, within the narrow spin-down $d$($e$) band and within the spin-up impurity band of the deep acceptor-level origin derived from the strong $p$-$d$($t_2$) hybridization. We conclude that the narrow $d$($e$) band is responsible for the ferromagnetic coupling between Fe atoms while the acceptor-level-originated band is responsible for the transport properties of Ge:Fe.

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Cited by in corpus (5)

• Electronic structure of the novel high-$T_{\mathrm{C}}$ ferromagnetic semiconductor (Ga,Fe)Sb: x-ray magnetic circular dichroism and resonance photoemission spectroscopy studies
• Minority-Spin Impurity Band in n-Type (In,Fe)As: A Materials Perspective for Ferromagnetic Semiconductors
• Magnetization process of the insulating ferromagnetic semiconductor (Al,Fe)Sb
• Development of magnetism in Fe-doped magnetic semiconductors: Resonant photoemission and x-ray magnetic circular dichroism studies of (Ga,Fe)As
• Impurity band conduction in group-IV ferromagnetic semiconductor Ge1-xFex with nanoscale fluctuations in Fe concentration