Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 67: Ultrafast Electron Dynamics II

O 67.5: Vortrag

Mittwoch, 19. März 2025, 16:00–16:15, H11

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. Beye^5,6, G. S. Chiuzbaian⁷, R. Carley⁴, R. Gort⁴, B. E. Van Kuiken⁴, G. Mercurio⁴, J. Schlappa⁴, A. Yaroslavtsev^4,8, A. Scherz⁴, F. Döring⁹, C. David⁹, H. Wende¹, U. Bovensiepen^1,10, M. Eckstein¹¹, P. Werner¹², and A. Eschenlohr¹ — ¹Univ. Duisburg-Essen & CENIDE — ²Jozef Stefan Inst. — ³Univ. of Ljubljana — ⁴European XFEL — ⁵DESY — ⁶Stockholm Univ. — ⁷Sorbonne Univ. — ⁸MAX IV Lab. — ⁹PSI — ¹⁰Univ. of Tokyo — ¹¹Univ. of Hamburg — ¹²Univ. of Fribourg

For strongly correlated materials, like the charge transfer insulator NiO, the interplay between the interaction-based localization and the itinerant behaviour of electrons is essential in determining the electronic properties. In these materials, resonant photoexcitations result in convoluted dynamics involving dynamical screening induced band shifts, charge redistributions and d-d type excitations. By combining fs time-resolved X-ray absorption spectroscopy and dynamical mean-field theory, we disentangle the intertwined dynamics. We find long-lived redshifts of the Ni L and O K edges (> 10 ps), arising from a combination of Hartree shifts and renormalization of local interactions. We also identify a short-lived Ni L ₃ pre-edge feature (< 1 ps) related to photo-induced d-d transitions [1]. Financial support by DFG through SFB 1242 is acknowledged. - [1] T. Lojewski et al., Phys. Rev. B, in press (ArXiv:2305.10145)

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