Formation of an incoherent metallic state in Rh-doped Sr2IrO4

We study with Angle-Resolved Photoemission the insulator to metal transition observed in Sr$_2$IrO$_4$ when $x$ Ir are substituted by Rh (0.02 0.07, is not a Fermi liquid. It is characterized by the absence of quasiparticles, unrenormalized band dispersion compared to calculations and a $\sim$30meV pseudo-gap on the entire FS. The originality of this behavior is that Ir and Rh, which are formally isovalent, adopt different charge states. We propose that results from different hybridization strength of Ir and Rh to oxygen.