Valence variations in the monolayer regime of Sm on the Nb(110) surface |
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Authors: | F. Strisland A. Ramstad C. Berg S. Raaen |
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Affiliation: | Norwegian University of Science and Technology (NTNU), N-7034 Trondheim, Norway |
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Abstract: | Sm overlayers in the monolayer regime, deposited on a Nb(110) single-crystal surface at room temperature, have been studied by means of high-resolution photoelectron spectroscopy of the Nb 3d5/2 core level and the Sm valence band. In the submonolayer regime, the Sm valence varies from mainly divalent for very low coverages to essentially trivalent close to a complete monolayer. Above 1 ML, a new divalent component appears in the Sm 4f spectra, corresonding to divalent Sm in the second layer. The mixed valence in this overlayer system is concluded to be heterogeneous (all Sm atoms have integer but site-dependent valence). Sm forms ordered overlayers on Nb(110) and the Sm growth is consistent with a layer-by-layer growth mode (Frank–van der Merwe growth). |
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Keywords: | Mixed valence Niobium Photoemission Samarium Samarium overlayers Surface |
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