The ABO₂ family of delafossite oxide metals has recently found renewed prominence, motivated by their rich materials properties ranging from ultra-high conductivity to unconventional magnetism [1,2]. I will discuss our angle-resolved photoemission (ARPES) studies on the bulk and surface electronic structure of the delafossite oxides (Pd,Pt)CoO₂.  I will show how a pronounced self-doping, occurring due to the polar nature of their surfaces, transforms the system from a single-band non-magnetic nearly-free electron metal in the bulk [3] to an itinerant ferromagnet with strong electron-magnon coupling [4], or to a correlated metal hosting a kinetic-energy-coupled inversion symmetry breaking [5] at their surfaces. The latter maximizes the influence of spin-orbit coupling, allowing this oxide surface to develop some of the largest Rashba-like spin splittings that are known. This ultimately suggests new routes to designing spintronic materials, and for driving the interplay of spin-orbit interactions and electronic correlations. Key collaborators on this work include Veronika Sunko (St Andrews and Max-Planck Institute for Chemical Physics of Solids, Dresden), Federico Mazzola (StA), and Helge Rosner, Pallavi Kushwaha, Seunghyum Khim, and Andy Mackenzie (MPI-CPFS).

[1] Ok et al., Phys. Rev. Lett. 111 (2013) 176405

[2] Mackenzie, Rep. Prog. Phys. 80 (2017) 032501

[3] Kushwaha, Sunko et al., Science Advances 1 (2015) e1500692

[4] Mazzola et al., arXiv:1710.05392 (2017)

[5] Sunko et al., Nature 549 (2017) 492