Bulk electronic properties ofFeSi1−xGexinvestigated by high-resolution x-ray spectroscopies

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We report an investigation of the bulk electronic properties of Fe in $\mathrm{Fe}{\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ ($x=0$, 0.11, 0.19, and 0.44) measured by high-resolution x-ray absorption spectroscopy at the $\mathrm{Fe}\phantom{\rule{0.2em}{0ex}}K$ edge, $\mathrm{Fe}\phantom{\rule{0.2em}{0ex}}K\ensuremath{\beta}$ x-ray emission, and $1s3p$ resonant x-ray emission spectroscopies. The emission data clearly show an increase in the magnetic moment when $x$ increases from 0 to 0.44. This doping-induced spin transition is accompanied by the onset of the magnetic order at $x\ensuremath{\geqslant}0.2$. The $1s3p$ resonant x-ray emission data reveal that the $\mathrm{Fe}\phantom{\rule{0.2em}{0ex}}3d$ states exhibit a delocalized character, while no intermediate valence admixture takes place. This is at odd with the intermediate valence Kondo insulator model and rather supports the local density approximation band theory.