Local density of states study of a spin-orbit-coupling induced Mott insulator Sr${}_2$IrO${}_4$

Abstract

We present scanning tunneling microscopy and spectroscopy experiments on the novel J_eff = 1/2 Mott insulator Sr2IrO4. Local density of states (LDOS) measurements show an intrinsic insulating gap of 620 meV that is asymmetric about the Fermi level and is larger than previously reported values. The size of this gap suggests that Sr2IrO4 is likely a Mott rather than Slater insulator. In addition, we found a small number of native defects which create in-gap spectral weight. Atomically resolved LDOS measurements on and off the defects shows that this energy gap is quite fragile. Together the extended nature of the 5d electrons and poor screening of defects help explain the elusive nature of this gap.

5 pages, 3 figures

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Cited by in corpus (37)

• The Challenge of Spin-Orbit-Tuned Ground States in Iridates
• Signature of high temperature superconductivity in electron doped Sr2IrO4
• Universality of pseudogap and emergent order in lightly doped Mott insulators
• The influence of electron-doping on the ground state of (Sr{1-x}La{x})2IrO4
• Square Lattice Iridates
• Coulomb Correlations in 4d and 5d Oxides from First Principles - or How Spin-Orbit Materials choose their Effective Orbital Degeneracies
• Transfer of spectral weight across the gap of Sr2IrO4 induced by La doping
• Carrier localization and electronic phase separation in a doped spin-orbit driven Mott phase in Sr3(Ir1-xRux)2O7
• Structure symmetry determination and magnetic evolution in $\mathrm{S}{\mathrm{r}}_2\mathrm{I}{\mathrm{r}}_{1-\mathrm{x}}\mathrm{R}{\mathrm{h}}_{\mathrm{x}}{\mathrm{O}}_4$
• Decoupling of the Antiferromagnetic and Insulating States in Tb doped Sr2IrO4
• Electrical Control of Structural and Physical Properties via Strong Spin-Orbit Interactions in Sr2IrO4
• Poor electronic screening in lightly doped Mott insulators observed with scanning tunneling microscopy
• Persistent Insulator: Avoidance of Metallization at Megabar Pressures in Strongly Spin-Orbit-Coupled Sr2IrO4
• Spectral functions of Sr${}_2$IrO${}_4$: theory versus experiment
• Perfect flat band with chirality and charge ordering out of strong spin-orbit interaction
• Bond Directional Anapole Order in a Spin-Orbit Coupled Mott Insulator Sr${}_2$(Ir${}_{1-x}$Rh${}_x$)O${}_4$
• Non-local Coulomb correlations in pure and electron-doped ${\mathrm{Sr}}_2{\mathrm{IrO}}_4$: spectral functions, Fermi surface and pseudogap-like spectral weight distributions from oriented cluster dynamical mean field theory
• Ambipolar Transport and Magneto-resistance Crossover in a Mott Insulator, Sr${}_2$IrO${}_4$
• High-energy electronic excitations in Sr${}_2$IrO${}_4$ observed by Raman scattering
• Tuning the electronic structure of Sr2IrO4 thin films by bulk electronic doping using molecular beam epitaxy
• Time resolved photoemission of Sr${}_2$IrO${}_4$
• Non-collinear vs collinear description of the Ir-based one-$t_{2g}$ -hole perovskite-related compounds: SrIrO${}_3$ and Sr${}_2$IrO${}_4$
• Emergent quantum phases in a frustrated J1-J2 Heisenberg model on hyperhoneycomb lattice
• Crystal structure and physical properties of the Sr-vacant spin-orbit-coupling induced Mott insulator Sr2-xIrO4
• Towards Electrical-Current Control of Quantum States in Spin-Orbit-Coupled Matter
• Percolative Mott insulator-metal transition in doped Sr${}_2$IrO${}_4$
• Decoupling of magnetism and electric transport in single-crystal (Sr1-xAx)2IrO4 (A = Ca or Ba)
• Modeling multiorbital effects in Sr2IrO4 under strain and a Zeeman field
• Ground state tuning of the metal-insulator transition by compositional variations in BaIr1-xRuxO3(0<x<1)
• Electrochemical Oxygen Intercalation into Sr${}_2$IrO${}_4$
• Evidence of Slater-type mechanism as origin of insulating state in Sr2IrO4
• Possible superconductivity induced by a large spin-orbit coupling in carrier doped iridium oxide insulators: A weak coupling approach
• Spin-polaron ladder spectrum of the spin-orbit-induced Mott insulator Sr${}_2$IrO${}_4$ probed by scanning tunneling spectroscopy
• Microscopic and Spectroscopic Evidence for a Slater Metal-Insulator Transition in Sr2IrO4
• Microscopic model realization of $\mathbf{d}$-wave pseudospin current order in Sr${}_2$IrO${}_4$
• Three-dimensional Stacking of Canted Antiferromagnetism and Pseudospin Current in Undoped Sr${}_2$IrO${}_4$: Symmetry Analysis and Microscopic Model Realization
• Fortuitous partners of antiferromagnetic and Mott states in spin-orbit-coupled Sr2IrO4: A study of Sr2Ir1-xMxO4 (M=Fe or Co)