  The simultaneous presence of sizable spin-orbit interactions and electron
correlations in iridium oxides has led to predictions of novel ground states
including Dirac semimetals, Kitaev spin liquids, and superconductivity.
Electron and hole doping studies of spin-orbit assisted Mott insulator Sr2IrO4
are being intensively pursued due to extensive parallels with the La2CuO4
parent compound of Cuprate superconductors. In particular, the mechanism of
charge doping associated with replacement of Ir with Rh ions remains
controversial with profound consequences for the interpretation of electronic
structure and transport data. Using x-ray absorption near edge structure
(XANES) measurements at the Rh L, K- and Ir L- edges we observe anomalous
evolution of charge partitioning between Rh and Ir with Rh doping. The
partitioning of charge between Rh and Ir sites progresses in a way that holes
are initially doped into the Jeff=1/2 band at low x only to be removed from it
at higher x values. This anomalous hole doping naturally explains the
re-entrant insulating phase in the phase diagram of Rh doped Sr2IrO4 and ought
to be considered when searching for superconductivity and other emergent
phenomena in iridates doped with 4d elements
