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arXiv · 1610.09839

La-doping effect on spin-orbit coupled Sr2IrO4 probed by x-ray absorption spectroscopy

Jie Cheng·Xuanyong Sun·Shengli Liu·Bin Li·Haiyun Wang·Peng Dong·Yu Wang·Wei Xu
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Abstract

Sr2IrO4 was predicted to be an unconventional superconductor upon carrier doping since it highly resembles the high-temperature cuprates. Here, to understand carrier doping effect on spin-orbit coupled Mott insulator Sr2IrO4, the electronic structure and local structure distortion for Sr2-xLaxIrO4 system have been investigated by x-ray absorption spectroscopy (XAS). By comparing the intensity of white-line features at the Ir L2,3 absorption edges, we observe remarkably large branching ratios in La-doped compounds, greater than that of the parent material Sr2IrO4, suggesting a strong spin-orbit interaction (SOI) for Sr2IrO4-based system. Moreover, extended x-ray absorption fine structure (EXAFS) spectra demonstrate more regular IrO6 octahedra, i.e. the weakened crystal electric field (CEF) versus La-doping. By theoretical calculations, the synergistic effect of regular IrO6 octahedra and electron doping is established, which accounts for the transition from a Mott insulator to a conductive state in Sr2-xLaxIrO4-based system.

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Jie Cheng, Xuanyong Sun, Shengli Liu, Bin Li, Haiyun Wang, Peng Dong, Yu Wang, Wei Xu. 2016-10-31. La-doping effect on spin-orbit coupled Sr2IrO4 probed by x-ray absorption spectroscopy. https://doi.org/10.1088/1367-2630%2F18%2F9%2F093019

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