Orbital-selective metal skin induced by alkali-metal-dosing Mott-insulating Ca${}_2$RuO${}_4$

Abstract

Doped Mott insulators are the starting point for interesting physics such as high temperature superconductivity and quantum spin liquids. For multi-band Mott insulators, orbital selective ground states have been envisioned. However, orbital selective metals and Mott insulators have been difficult to realize experimentally. Here we demonstrate by photoemission spectroscopy how Ca${}_2$RuO${}_4$, upon alkali-metal surface doping, develops a single-band metal skin. Our dynamical mean field theory calculations reveal that homogeneous electron doping of Ca${}_2$RuO${}_4$ results in a multi-band metal. All together, our results provide compelling evidence for an orbital-selective Mott insulator breakdown, which is unachievable via simple electron doping. Supported by a cluster model and cluster perturbation theory calculations, we demonstrate a novel type of skin metal-insulator transition induced by surface dopants that orbital-selectively hybridize with the bulk Mott state and in turn produce coherent in-gap states.

A revised version of this manuscript will appear in Communications Physics

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Cited by in corpus (3)

• Low-energy interband Kondo bound states in orbital-selective Mott phases
• Magnetic polarons due to spin-length fluctuations in ${\mathbf{d}}^4$ spin-orbit Mott systems
• Origin of dimensional crossover in quasi-one-dimensional hollandite K${}_2$Ru${}_8$O${}_{16}$