We investigate the effect of Rh doping in Sr2IrO4 using X-ray absorption spectroscopy (XAS). We observed appearance of new electron-addition states with increasing Rh concentration (x in Sr2Ir1−xRhxO4) in accordance with the concept of hole doping. The intensity of the hole-induced state is however weak, suggesting weakness of charge transfer (CT) effect and Mott insulating ground states. Also, Ir Jeff = 1/2 upper Hubbard band shifts to lower energy as x increases up to x = 0.23. Combined with optical spectroscopy, these results suggest a hybridisation-related mechanism, in which Rh doping can weaken the (Ir Jeff = 1/2)–(O 2p) orbital hybridisation in the in-planar Rh-O-Ir bond networks.
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This work was supported by IBS-R009-D1. D.-Y.C. acknowledges support from Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT and Future Planning (NRF-2015R1C1A1A02037514). G.C. acknowledges support by the U.S. National Science Foundation via Grant No. DMR-1265162.
Sohn, C. H.; Cho, Deok-Yong; Kuo, C. -T.; Sandilands, L. J.; Qi, Tongfei; Cao, Gang; and Noh, T. W., "X-ray Absorption Spectroscopy Study of the Effect of Rh Doping in Sr2IrO4" (2016). Center for Advanced Materials Faculty Publications. 5.