Abstract
We use soft x-ray photoemission spectroscopy (SXPES) to investigate Ce electronic states of a new layered superconductor , for polycrystalline and single-crystal samples. The Ce spectrum of the single crystal of nominal composition has no component and the spectral shape closely resembles the ones observed for Ce trivalent insulating compounds, strongly implying that the CeO layer is still in an insulating state even after the F doping. The Ce resonant SXPES for both polycrystalline and single-crystal samples shows that the prominent peak is located around 1 eV below the Fermi level with negligible spectral intensity at . The F-concentration dependence of the valence band spectra for single crystals shows the increases of the degeneracy in energy levels and of the interaction between Ce and S states. These results give insight into the nature of the layer and the microscopic coexistence of magnetism and superconductivity in .
- Received 19 November 2015
- Revised 16 December 2016
DOI:https://doi.org/10.1103/PhysRevB.95.085109
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