Enhanced insulating behavior in the Ir‐vacant Sr2Ir1–xO4 system dominated by the local structure distortion. (29th May 2018)

• Record Type: Journal Article
• Authors: Cheng, Jie; Dong, Peng; Li, Bin; Liu, Shengli; Wang, Xiangfu; Wang, Yu; Li, Xing'ao
• Is Part Of: Journal of synchrotron radiation. Volume 25:Part 4(2018)
• Page Start: 1123
• Page End: 1128
• Publication Date: 2018-05-29
• Subjects: Sr2Ir1–xO4 -- X‐ray absorption spectroscopy -- local structure distortion; Synchrotron radiation -- Periodicals; Free electron lasers -- Periodicals; 539.73505
• DOI: 10.1107/S1600577518005799
• Languages: English
• ISSNs: 0909-0495

Abstract

Abstract : X‐ray absorption spectroscopy was applied to study the enhanced insulating behavior in the Ir‐vacant Sr2 Ir1– x O4 system. Data pointed out that both the more distorted IrO6 octahedra and decreased Ir—O1—Ir angle contribute to the increment of the band gap, and then result in the enhanced insulating state for Sr2 Ir1– x O4 . Abstract : Sr2 IrO4, known as the J eff = 1/2 Mott insulator, was predicted to be an unconventional superconductor upon doping since it highly resembles the high‐temperature cuprates. However, recent work pointed out an enhanced insulating behavior in the Ir‐vacant Sr2 Ir1– x O4 system. In this contribution, to investigate the microscopic mechanism of its enhanced insulating behavior, X‐ray absorption spectroscopy was applied to study the electronic structure and local structure distortion of Sr2 Ir1– x O4 . Due to the presence of Ir 5+ ions, the preconceived holes are barely doped in the Ir‐vacant system. Nevertheless, Ir vacancies finely modulate the local atomic structure, i.e. the topology of IrO6 octahedra and the in‐plane Ir—O1—Ir bond angle. Combined with theoretical calculations, it is demonstrated that both the more distorted IrO6 octahedra and decreased Ir—O1—Ir angle contribute to the increment of the band gap, and then result in the enhanced insulating state for Sr2 Ir1– x O4 .