Indium Preferential Distribution Enables Electronic Engineering of Magnetism in FeSb2–xInxSe4 p-Type High-Tc Ferromagnetic Semiconductors

Single-phase samples of the solid-solution series FeSb2–xInxSe4 (0 ≤ x ≤ 0.25) were synthesized using solid-state reaction of the elements to probe the effect of electronic structure engineering on the magnetic behavior of the p-type semiconductor, FeSb2Se4. Powder X-ray diffraction data suggest that all samples are isostructural with FeSb2Se4. Rietveld refinements of the distribution of In atoms at various metal positions indicate a preferential substitution of Sb at the M1(4i) position within the magnetic layer A for In concentration up to x = 0.1. FeSb2–xInxSe4 compositions with higher In content show the distribution of In atoms at all metal positions, except for the M3(2d), which is fully occupied by Fe atoms. Interestingly, the ordering of Fe atoms within the crystal structure of FeSb2–xInxSe4 remains essentially unaffected by the degree of substitution (x values) and is comparable to the distribution of Fe atoms reported in FeSb2Se4. X-ray photoelectron spectroscopy confirms the oxidation states of...