Abstract
We study the electronic structure of single-crystal , a non-charge-ordered mixed-valent semiconductor which exhibits a glassy magnetic ground state. We use the techniques of soft x-ray photoemission, hard x-ray photoemission, x-ray absorption, and resonant photoemission spectroscopy to investigate the occupied and unoccupied electronic states of . Core level photoemission and x-ray absorption spectroscopy allow us to determine the valence states of Tb, Sr, and Mn ions in . Model charge transfer multiplet calculations of core level photoemission and x-ray absorption spectra are employed to separate out the and states and confirm their relative concentrations. Resonant photoemission spectroscopy across the Mn threshold shows clear resonant enhancement of the Mn partial density of states and two-hole correlation satellites. A Cini-Sawatzky analysis gives on-site Coulomb energy eV for the Mn states and = 0.7 eV for the Mn states. The O resonant photoemission is used to identify the O two-hole correlation satellite which provides eV for the O states. Valence band photoemission indicates a small-gap semiconductor ( meV) consistent with electrical transport measurements. The estimated electronic structure parameters of the on-site Coulomb energies, in combination with the charge transfer energy and the hybridization strength obtained from the model calculations, indicate that is a strongly correlated charge transfer type semiconductor.
6 More- Received 30 March 2021
- Accepted 27 May 2021
DOI:https://doi.org/10.1103/PhysRevB.103.245131
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