Local electronic structure of RuO₂

Despite being historically identified as a paramagnetic semi-metal, RuO₂ has received heightened interest for its recently discovered itinerant antiferromagnetism, novel Hall effects and strain-induced superconductivity. Microscopic understanding and further manipulation of these properties demands resolving the relative roles of the unique rutile crystal field and 4d spin-orbit coupling in the electronic structure. In this talk, I will discuss recent results of M₃-edge (3p-4d) resonant inelastic X-Ray scattering experiments on bulk RuO₂. Through identification of the dd-excitations, their resonance behavior and comparison to multiplet calculations, we are able to place definitive constraints on the contributions of the low-symmetry crystal field and spin-orbit coupling in the local orbital energetics. Our results have implications for the balance of these interactions across the 3d, 4d and 5d rutile oxides and provide a path toward determining the local strain-induced orbital modifications which result in superconductivity.