Crystal field effect in spin-orbit Mott insulating Sr3NiIrO6
Jun Okamoto1*, Wen-Bin Wu1, Hirofumi Ishii1, Kuan-Li Yu1, Nozomu Hiraoka1, Ru-Pan Wang1, Deng-Ming Juo2, Jiunn Chen3, Viveka Singh4, Guang-Yu Guo4, Qinghui Jiang5, Sang-Wook Cheong6, Ku-Ding Tsuei1, Di-Jing Huang1
1National Synchrotron Radiation Research Center, Hsinchu, Taiwan
2National Chiao Tung University, Hsinchu, Taiwan
3National Pingtung University of Education, Pingtung, Taiwan
4National Taiwan University, Taipei, Taiwan
5Postech, Pohang, Korea
6Rutgers Unversity, New Jersey, United States of America
* presenting author:Jun Okamoto,
Sr3NiIrO6 is a member of 5d transition-metal Ir oxides with a long chain alternating Ni2+ in trigonal prismatic coordination and Ir4+ in octahedral coordination along c axis. Sr3NiIrO6 is considered to be a spin-orbit Mott insulator like Sr2IrO4. Since the Ir 5d spin-orbit coupling (SOC) and crystal field (CF) effect in t2g orbitals from trigonal distortion are comparable, however, competition between the SOC and CF effect makes the Ir 5d electronic structures different from the so-called jeff = 1/2 ground state. The modified Ir 5d electronic structures under the trigonal crystal field effect are still unclear.
We have studied the Ir 5d electronic structures of Sr3NiIrO6 by using Ir L3-edge resonant inelastic x-ray scattering and O K-edge x-ray absorption spectroscopy measurements.
Through the analyses of the low-energy d-d excitations and the unoccupied Ir 5d states, we discuss the influence of the competition of SOC and CF effects on the Ir 5d electronic structures of Sr3NiIrO6.

Keywords: Ir oxide, spin-orbit interaction, crystal field, resonant inelastic x-ray scattering, x-ray absorption spectroscopy