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  Liu, C.-Y.; Celiberti, L.; Decker, R.; Ruotsalainen, K.; Siewierska, K.; Kusch, M.; Wang, R.-P.; Kim, D. J.; Olaniyan, I.I.; Di Castro, D.; Tomiyasu, K.; van der Minne, E.; Birkhölzer, Y.A.; Kiens, E.M.; van den Bosch, I.C.G.; Patil, K.N.; Baeumer, C.; Koster, G.; Lazemi, M.; de Groot, F.M.F.; Dubourdieu, C.; Franchini, C.; Föhlisch, A.: Orbital-overlap-driven hybridization in 3d-transition metal perovskite oxides LaMO₃ (M = Ti-Ni) and La₂CuO₄. Communications Physics 7 (2024), p. 156/1-7

10.1038/s42005-024-01642-5
Open Access Version

Abstract:
The wide tunability of strongly correlated transition metal (TM) oxides stems from their complex electronic properties and the coupled degrees of freedom. Among the perovskite oxides family, LaMO3 (M = Ti-Ni) allows an M-dependent systematic study of the electronic structure within the same-structure-family motif. While most of the studies have been focusing on the 3d TMs and oxygen sites, the role of the rare-earth site has been far less explored. In this work, we use resonant inelastic X-ray scattering (RIXS) at the lanthanum N4,5 edges and density functional theory (DFT) to investigate the hybridization mechanisms in LaMO3.We link the spatial-overlap-driven hybridization to energeticoverlap-driven hybridization by comparing the RIXS chemical shifts and the DFT band widths. The scope is extended to highly covalent Ruddlesden-Popper perovskite La2CuO4 by intercalating lanthanum atoms to rock-salt layers. Our work evidences an observable contribution of localized lanthanum 5p and 4f orbitals in the band structure.