Electronic structure of the high- TC ferromagnetic semiconductor (Ga,Fe)Sb: X-ray magnetic circular dichroism and resonance photoemission spectroscopy studies

Abstract

The electronic structure and the magnetism of the novel ferromagnetic semiconductor (Ga,Fe)Sb, whose Curie temperature T C can exceed room temperature, were investigated by means of x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and resonance photoemission spectroscopy (RPES). The line-shape analyses of the XAS and XMCD spectra suggest that the ferromagnetism is of intrinsic origin. The orbital magnetic moments deduced using XMCD sum rules were found to be large, indicating that there is a considerable amount of 3d 6 contribution to the ground state of Fe. From RPES, we observed a strong dispersive Auger peak and non-dispersive resonantly enhanced peaks in the valenceband spectra. The latter is a fingerprint of the correlated nature of Fe 3d electrons, whereas the former indicates their itinerant nature. It was also found that the Fe 3d states have finite contribution to the DOS at the Fermi energy. These states presumably consisting of majority-spin p-d hybridized states or minority-spin e states would be responsible for the ferromagnetic order in this material.

Densities of states in Fe-doped III-V semiconductors: a first-principles study

“…The intermediate systems such as (Ga,Fe)As or (Al,Fe)Sb showed the total magnetic moment slightly smaller than 5 The orbital magnetic moment relative to the spin magnetic moment (m l /m s ) increases from 0.015 to 0.061 as a host semiconductor becomes heavier and spin-orbit interaction becomes stronger. This is consistent with the previous x-ray magnetic circular dichroism (XMCD) experiments, where m l /m s is 0.1 for (In,Fe)As [30] and 0.13 for (Ga,Fe)Sb [31].…”

Evolution of Fe 3d impurity band state as the origin of high Curie temperature in the p -type ferromagnetic semiconductor (Ga,Fe)Sb

“…Besides the main peak at ∼ 708 eV, there is a shoulder structure at ∼ 710 eV in the XAS spectra of (Ga,Fe)Sb. The previous XMCD and RPES studies 26 showed that the shoulder component can be attributed to Fe 3+ oxides (such as α-Fe2O3) and is not related to the ferromagnetism in (Ga1-x,Fex)Sb. The oxidized components in the present capped (Ga,Fe)Sb samples are less than that in a previous uncapped (Ga,Fe)Sb thin film 26 , suggesting that the surface of our samples is well protected by the amorphous Sb capping layer from oxidation.…”

“…To characterize the x dependence of the Fe-3d PDOS in the VB structure, we have conducted RPES measurements on the (Ga1-x,Fex)Sb (x = 0.05, 0.15, and 0.25) thin films and analyzed the spectra in detail. The resonant enhancement of the photoemission intensity measured at hν = 708 eV should reflect the energy position of the ferromagnetic component of Fe 3d states in (Ga1-x,Fex)Sb, because Fe L3 XMCD has a prominent peak at hν = 708 eV, the intensity of which as a function of magnetic field shows a ferromagnetic behavior 26 . Figure 2(a) shows the RPES spectra of the (Ga1-x,Fex)Sb thin films taken at hν = 708 eV (on-resonance) and hν = 704 eV (off-resonance), respectively.…”

“…As for (Ga,Fe)Sb, some experimental 26,27,28 and theoretical 29,30,31 studies on its electronic structure were performed to understand the mechanism of the carrier-induced ferromagnetism. The local electronic structure, magnetic properties of Fe ions, and the valence-band (VB) structure were investigated by x-ray absorption spectroscopy (XAS),…”

“…x-ray magnetic circular dichroism (XMCD), and resonant photoemission spectroscopy (RPES) 26 . From these experiments, it was found that Fe ions in (Ga,Fe)Sb take the 3d 6 configuration, which has both itinerant and correlated nature of 3d electrons, and there is a finite Fe partial density of states (PDOS) at the Fermi level (EF).…”