Enhanced insulating behavior in the Ir-vacant Sr2Ir1 – xO4 system dominated by the local structure   distortion

Sr2IrO4, known as the Jeff = 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 Sr2Ir1 – xO4 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 Sr2Ir1 – xO4. Due to the presence of Ir5+ 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 Sr2Ir1 – xO4.

Source: Journal of Synchrotron Radiation - May 29, 2018 Category: Physics Authors: Cheng, J. Dong, P. Li, B. Liu, S. Wang, X. Wang, Y. Li, X. Tags: Sr2Ir1 – xO4 X-ray absorption spectroscopy local structure distortion research papers Source Type: research