Electronic reconstruction in confined SrRuO 3 monolayers

We report the observation of an electronic reconstruction in dimensionally controlled ruthenate heterostructures synthesized by pulsed laser deposition. High structural and electronic quality of superlattices comprised of a single ${\mathrm{SrRuO}}₃$ layer inter-spaced with varying thicknesses of insulating ${\mathrm{SrTiO}}₃$ layers was verified by reflection high energy electron diffraction, atomic force microscopy, x-ray diffraction, reciprocal space mapping, and x-ray absorption spectroscopy. X-ray absorption spectroscopy evidences a confinement-driven evolution of the Ru electronic configuration from the ${d}⁵\underline{L}$ to the ${d}⁴$ state. Significant increases of the spin-orbit coupling are observed in connection with the configuration changes supporting recent works identifying large enhancement of the magnetic anisotropy. The growth of high quality two-dimensional confined ruthenate layers under precisely controlled environments highlights the potential to directly manipulate interlayer coupling and selectively perturb the electronic state in ruthenates in analogy to superconducting ${\mathrm{Sr}}₂{\mathrm{RuO}}₄$.