Honeycomb lattice Na2IrO3 at high pressures: A robust spin-orbit Mott insulator

Authors

• Xiaoxiang Xi, Nanjing University, ChinaFollow
• Xiangyan Bo, Nanjing University, China
• X. S. Xu, University of Nebraska-LincolnFollow
• P. P. Kong, Chinese Academy of Sciences
• Z. Liu, The George Washington University
• X. G. Hong, Stony Brook University
• C. Q. Jin, Chinese Academy of Sciences
• G. Cao, University of Colorado Boulder
• Xiangang Wan, Nanjing University, ChinaFollow
• G. L. Carr, Brookhaven National Laboratory

Document Type

Article

Date of this Version

2018

Citation

PHYSICAL REVIEW B 98, 125117 (2018)

Comments

Used by permission.

Abstract

The honeycomb iridate Na₂IrO₃ has received much attention as a candidate to realize a quantum spin liquid state, but the nature of its insulating state remains controversial. We found that the material exhibits structural transitions at 3 and 10 GPa. The former is accompanied by 166-meV suppression of the activation gap, but the energies for the low-lying interband transitions change by less than 10 meV. This can be reconciled in a picture in which the application of high pressure barely shifts the electronic bands, but rather merely broadens them. First-principles calculations uncover a strong correlation between the band gap and the β angle of the monoclinic structure, indicating non-negligible interlayer coupling. These results offer clear evidence for a spin-orbit Mott insulating state in Na₂IrO₃ and are inconsistent with the quasimolecular orbital model.