Regensburg 2022 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 23: Computational Materials Modelling: Magnetic & Electrical Properties
MM 23.6: Vortrag
Mittwoch, 7. September 2022, 17:15–17:30, H44
Energetic and electronic properties of CsK2Sb surface facets: An ab initio study — •Richard Schier1,2, Holger-Dietrich Saßnick2, and Caterina Cocchi2,1 — 1Humboldt-Universität zu Berlin and IRIS Adlershof — 2Carl von Ossietzky Universität Oldenburg
For the efficient generation of ultra-bright electron beams, the microscopic understanding of the electronic structure of the photoemitting materials is crucial. Ternary alkali antimonides have been proposed as a promising class of photocathodes [1-4]. However, still little is known about their surface properties. We fill this gap with an ab initio study of the energetic and electronic properties of 7 CsK2Sb surface facets of low Miller index. We investigate formation energies as a function of chemical potential to quantify the stability of these systems at varying concentration of the atomic species. We find that the (111)-surfaces terminated with K on top of Sb are generally the most stable, except for very high (low) concentrations of Cs (K). Calculated values for the work functions range from 2.33 eV for (100)-surfaces to 3.50 eV for (111)-surfaces terminated with a Sb layer. From the analysis of the band structures we find 4 out of 7 surfaces to be semiconducting. Metallic surfaces are formed upon an excess of metal atoms at the interface with vacuum.
[1] Schmeißer et al., PRAB 21, 113401 (2018). [2] Cocchi et al., JPCM 31, 014002 (2019). [3] Cocchi et al., Sci. Rep. 9, 18276 (2019). [4] Amador & Cocchi, JPCM 33, 365502 (2021).