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O: Fachverband Oberflächenphysik
O 53: Focus Session: Frontiers of Electronic-Structure Theory IV (joint session O/HL)
O 53.8: Talk
Wednesday, March 29, 2023, 12:45–13:00, TRE Ma
Electronic and optical properties of CoFe2O4 from density functional theory calculations, including many-body effects — •Shohreh Rafiezadeh1, Vijaya Begum-Hudde1,2, and Rossitza Pentcheva1 — 1Department of Physics University of Duisburg-Essen, Germany — 2University of Illinois at Urbana-Champaign, USA
CoFe2O4 is a ferrimagnetic semiconductor that finds application as an anode material in photocatalytic water splitting. We present a comprehensive study of the electronic and optical properties of bulk CoFe2O4 using density functional theory calculations and many-body perturbation theory to clarify the broad range of reported band gaps both experimentally (0.55-4.1 eV)[1] and theoretically (0.9-1.90 eV). Starting with different exchange-correlation functionals, we obtain a direct band gap of 1.38 [PBE+(U=4 eV)], 1.69 eV [SCAN+(U=3 eV)], and an indirect gap of 2.02 eV (HSE06). Including quasiparticle corrections within G0W0 enhances and renders indirect band gaps for all functionals of 1.78, 1.95 and 2.17 eV, respectively. Excitonic effects are accounted for by solving the Bethe Salpeter equation and result in the lowest threshold for optical transitions at 1.50 eV (SCAN) and 1.61 eV (HSE06), followed by peaks at ∼ 2.0, 3.5 and 5.0 eV, in agreement with experiment highlighting the importance of electron-hole interactions. Support by DFG- within CRC/TRR 247, project B04, and computational time at MagnitUDE is gratefully acknowledged. [1] S. Singh and N. Khare, Sci. Rep. 8, 6522 (2018).