Investigation of unconventional reconstruction and electronic properties on the Na2IrO3 surface

Abstract

Na2IrO3 is an intriguing material for which spin-orbit coupling plays a key role. Theoretical predictions, so far unverified, have been made that the surface of Na2IrO3 should exhibit a clear signature of the quantum spin Hall effect. We studied the surface of Na2IrO3 using scanning tunneling microscopy and density-functional theory calculations. We observed atomic level resolution of the surface and two types of terminations with different surface periodicity and Na content. By comparing bias-dependent experimental topographic images to simulated images, we determined the detailed atomistic structure of both observed surfaces. One of these reveals a strong relaxation to the surface of Na atoms from the subsurface region two atomic layers below. Such dramatic structural changes at the surface cast doubt on any prediction of surface properties based on bulk electronic structure. Indeed, using spatially resolved tunneling spectroscopy we found no indication of the predicted quantum spin Hall behavior.

References in corpus (8)

• Kitaev-Heisenberg Model on Honeycomb Lattice: Possible Exotic Phases in Iridium Oxides $A_2$IrO${}_3$
• Mott physics and band topology in materials with strong spin-orbit interaction
• Spin waves and revised crystal structure of honeycomb iridate Na2IrO3
• Quantum spin Hall effect in a transition metal oxide Na2IrO3
• Na2IrO3 as a spin-orbit-assisted antiferromagnetic insulator with a 340 meV gap
• Possible proximity of the Mott insulating Iridate Na2IrO3 to a topological phase: Phase diagram of the Heisenberg-Kitaev model in a magnetic field
• Ab initio analysis of the tight-binding parameters and magnetic interactions in Na2IrO3
• Na2IrO3 as a molecular orbital crystal

Cited by in corpus (9)

• Models and Materials for Generalized Kitaev Magnetism
• Observation of metallic surface states in the strongly correlated Kitaev-Heisenberg candidate Na2IrO3
• Quasiparticles and charge transfer at the two surfaces of the honeycomb iridate Na${}_2$IrO${}_3$
• First order density wave like transitions in surface doped Na${}_2$IrO${}_3$
• Conductivity of Dirac-like surface states in correlated honeycomb transition metal oxide Mott insulators
• Dynamic Surface Modification due to Effusion of Na in Na${}_2$IrO${}_3$
• Spin-polaron ladder spectrum of the spin-orbit-induced Mott insulator Sr${}_2$IrO${}_4$ probed by scanning tunneling spectroscopy
• Enhanced Magnetism and Phase Transitions in Ultrathin Quantum Spin Liquid Na2IrO3 Flakes
• Metallic conductivity on Na-deficient structural domain walls in the spin-orbit Mott insulator Na${}_2$IrO${}_3$