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Abstract

We present an electronic structure study of the quasi-one-dimensional chalcogenide BaFe₂Se₃ using resonant inelastic x-ray scattering (RIXS) at the Fe L₃ edge. In addition to broad spectral contributions from fluorescence, sharp peaks are seen at the low-energy end of the spectra, suggesting the coexistence of both band and localized properties in this compound up to the antiferromagnetic transition temperature. The width of the fluorescence line can be accounted for by band structure calculations, while the positions of the sharp peaks are in good agreement with crystal-field multiplet calculations. At measurement temperatures below 300 K, the temperature dependence of the low-energy part of the spectra is accounted for by the changes in thermal occupation of closely lying energy states. At 300 K, however, a substantial broadening of the spectra is observed at low-energy loss, which is consistent with the closure of the antiferromagnetic band gap.