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O: Fachverband Oberflächenphysik

O 13: Ultrafast Electron Dynamics at Surfaces and Interfaces II

O 13.2: Talk

Monday, March 18, 2024, 15:30–15:45, MA 041

Photo-induced charge-transfer renormalization in NiO — •T. Lojewski¹, D. Golez^2,3, K. Ollefs¹, L. Le Guyader⁴, L. Kämmerer¹, N. Rothenbach¹, R. Y. Engel⁵, P. S. Miedema⁵, M. Beye⁵, G. S. Chiuzbaian⁶, R. Carley⁴, R. Gort⁴, B. E. Van Kuiken⁴, G. Mercurio⁴, J. Schlappa⁴, A. Yaroslavtsev^4,7, A. Scherz⁴, F. Döring⁸, C. David⁸, H. Wende¹, U. Bovensiepen^1,9, M. Eckstein¹⁰, P. Werner¹¹, and A. Eschenlohr¹ — ¹Univ. Duisburg-Essen and CENIDE — ²Jozef Stefan Inst. — ³Univ. of Ljubljana — ⁴European XFEL — ⁵DESY — ⁶Sorbonne Univ. — ⁷Uppsala Univ. — ⁸PSI — ⁹Univ. of Tokyo — ¹⁰Univ. of Hamburg — ¹¹Univ. of Fribourg

Strongly correlated materials, such as the charge transfer insulator NiO, exhibit fascinating properties due to the interaction-induced localisation of electrons, which competes with their itinerant nature. Here, optical excitation of charge carriers, i.e. photodoping, results in complex dynamics involving both d-p and d-d excitations. Through a resonant optical pump, femtosecond time-resolved X-ray absorption probe experiment in combination with dynamical mean-field theory, we analyse these dynamics in photo-doped NiO. We find a redshift of the Ni L ₃ and O K edges (persisting for > 10 ps), relating to a simultaneous occurrence of Hartree shifts and a renormalisation of local interactions. In addition, we observe a feature below the Ni L ₃ edge (at < 1 ps), which we relate to a transient nonthermal population of local many-body multiplets [1]. Financial support by DFG through SFB 1242 is acknowledged. - [1] T. Lojewski et al., arXiv:2305.10145

Keywords: ultrafast electron dynamics; strongly correlated materials; time-resolved x-ray spectroscopy