Orbital engineering in YVO3-LaAl O3 superlattices

Abstract

Oxide heterostructures provide unique opportunities to modify the properties of quantum materials through a targeted manipulation of spin, charge, and orbital states. Here, we use resonant x-ray reflectometry to probe the electronic structure of thin slabs of YVO3 embedded in a superlattice with LaAlO3. We extend the previously established methods of reflectometry analysis to a general form applicable to t2g electron systems and extract quantitative depth-dependent x-ray linear dichroism profiles. Our data reveal an artificial, layered orbital polarization, where the average occupation of xz and yz orbitals in the interface planes next to LaAlO3 is inverted compared to the central part of the YVO3 slab. This phase is stable down to 30 K and the bulklike orbital ordering transitions are absent. We identify the key mechanism for the electronic reconstruction to be a combination of epitaxial strain and spatial confinement by the LaAlO3 layers, in good agreement with predictions from ab initio theory.