Unravelling uniaxial strain effects on electronic correlations, hybridization and bonding in transition metal oxides

The interplay among spin, lattice, charge and orbit is of central importance for several rich and fascinating properties of oxides, and is the subject of intense research at present. Here, we present an approach to manipulate this interplay by Sn doping to effectively apply uniaxial strain on the TiO₂ lattice. The evolution of this interplay in pseudo-homoepitaxial Ti_1-xSn_xO₂ films is measured using a combination of X-ray absorption near edge spectroscopy at the O K and Ti L_3,2-edges. Supported by various theoretical calculations, we find that the multiplet-type electronic correlations, long-range bonding and hybridization in the system can be controlled by independently modifying uniaxial strain, thereby allowing us to establish the correlations among these effects, doping concentration, and strain. This significantly widens the phase space for experimental exploration of predictive models and leads to new possibilities for manipulation over materials’ functional properties. The methodology presented here can be applied in general to study the nature of the multiplet-type electronic correlations and bonding properties in octahedral-coordinated 3d^N transition metal oxides.