La-doping effect on spin-orbit coupled Sr2IrO4 probed by x-ray absorption spectroscopy
La-doping effect on spin-orbit coupled Sr2IrO4 probed by x-ray absorption spectroscopy
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X射线吸收光谱探测La掺杂对自旋轨道耦合Sr2IrO4的影响
DOI：
10.1088/1367-2630/18/9/093019
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发表时间：
2016
影响因子：
3.3
通讯作者：
Xu Wei
中科院分区：
文献类型：
--
作者：
Cheng Jie;Sun Xuanyong;Liu Shengli;Li Bin;Wang Haiyun;Dong Peng;Wang Yu;Xu Wei
Sr2IrO4与高温铜氧化物非常相似，被认为是一种非传统的载流子掺杂超导体。为了了解载流子掺杂对自旋轨道耦合Mott绝缘体Sr2IrO4的影响，利用X射线吸收光谱研究了Sr2 − xLaxIrO4系统的电子结构和局域结构畸变.通过比较Ir L2，3吸收边的白线特征强度，我们观察到La掺杂的化合物中有非常大的分支比，大于母体材料Sr2 IrO4的分支比，表明Sr2 IrO4基体系具有很强的自旋轨道相互作用.此外，扩展的X射线吸收精细结构谱表明更规则的IrO 6八面体，即与La掺杂的晶体电场减弱。通过理论计算，建立了规则IrO6八面体和电子掺杂的协同效应，解释了Sr2 − xLaxIrO4基体系从Mott绝缘态到导电态的转变.
Sr 2 IrO 4 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 Sr 2 IrO 4, the electronic structure and local structure distortion for Sr 2− x La x IrO 4 system have been investigated by x-ray absorption spectroscopy. By comparing the intensity of white-line features at the Ir L 2, 3 absorption edges, we observe remarkably large branching ratios in La-doped compounds, greater than that of the parent material Sr 2 IrO 4, suggesting a strong spin-orbit interaction for Sr 2 IrO 4-based system. Moreover, extended x-ray absorption fine structure spectra demonstrate more regular IrO 6 octahedra, ie the weakened crystal electric field versus La-doping. By theoretical calculations, the synergistic effect of regular IrO 6 octahedra and electron doping is established, which accounts for the transition from a Mott insulator to a conductive state in Sr 2− x La x IrO 4-based system.