Download Interplay between Anisotropic Hopping Interaction and Spin

Spectroscopic Investigation on the Electronic Structure of Na2IrO3: Interplay between
Anisotropic Hopping Interaction and Spin-Orbit Coupling
C. H. Sohn ,1,* H. S. Kim,2 T. F. Qi,3 D. W. Jeong,1 Hyun-Ju Park,1 H. K. Yoo,1 H. H. Kim,2 J. -Y.
Kim,4 T. D. Kang,1 G. Cao,3 J. Yu,2 S. J. Moon,5 and T. W. Noh1
1
Center for Functional Interfaces of Correlated Electron Systems, Institute for Basic Science, and
Department of physics & Astronomy, Seoul National University, Seoul 151-747, Korea
2
Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
3
Center for Advanced Materials, Department of Physics and Astronomy, University of Kentucky,
Lexington, Kentucky 40506, USA
4
Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 790-784,
Korea
5
Department of Physics, Hanyang University, Seoul 133-791, Korea
*Email of Presenting Author: [email protected]
Recently, iridates with honeycomb structure such as Na2IrO3 have received much attention due to
the expected novel quantum phases. For example, topological nontrivial band structure and quantum
spin liquid ground state are predicted theoretically. However, despite the great interest on this
compound, the electronic structure of Na2IrO3 still remain vague up to now. In this work, we
experimentally investigate on the electronic structure of Na2IrO3. We observe that the electronic
structures including orbital character in Na2IrO3 are mainly determined by anisotropic hopping
interaction as well as spin-orbit coupling. The optical conductivity data show complex multipeak
structure that can be understood in terms of the combined effects of spin-orbit coupling and
anisotropic hopping interaction. We also observe how anisotropic hopping interaction modifies the
orbital character of Na2IrO3 from atomic Jeff=1/2 orbitals. Polarization-dependent O 1s x-ray
absorption spectroscopy reveals that the valence states of Ir ions is described by the hybridized
orbitals of the Jeff = 1/2 state of an Ir atom and the Jeff=3/2 state of the neighboring Ir atom on a
hexagon.