Formation Of An Incoherent Metallic State In Rh-Doped Sr2iro4

Sr2IrO4 is the archetype of the spin-orbit Mott insulator, but the nature of the metallic states that may emerge from this type of insulator is still not very well known. We study with angle-resolved photoemission the insulator-to-metal transition observed in Sr2Ir1-xRhxO4 when Ir is substituted by Rh (0.02 < x < 0.35). The originality of the Rh doping is that Ir and Rh, which are formally isovalent, adopt different charge states, a rather unusual and inhomogeneous situation. We show that the evolution to the metallic state can be essentially understood as a shift of the Fermi level into the lower Hubbard band of Sr2IrO4. The Mott gap appears quite insensitive to the introduction of up to similar to 20% holes in this band. The metallic phase, which forms for x > 0.07, is not a Fermi liquid. It is characterized by the absence of quasiparticles, unrenormalized band dispersion compared to calculations, and an similar to 30-meV pseudogap on the entire Fermi surface.