Direct observation of the Mott gap in strontium iridate with a scanning tunneling microscope

Abstract

The single-layer Mott insulator strontium iridate Sr${}_2$IrO${}_4$ was studied using a scanning tunneling microscope. This measurement technique is unique due to the transport properties of this Mott insulator allowing tunneling measurements to be performed, even at cryogenic temperatures. We obtained high-resolution images of the sample surface and the differential tunneling conductance at different cryogenic temperatures. The differential conductance is a direct measurement of the local electronic density of states which provided an insulating gap consistent with optical conductivity, angle resolved photoemission spectroscopy and resonant inelastic x-ray scattering (RIXS) experiments. The observed widths of these features is broader than predicted by the Slater approximation and narrower than predicted by dynamical mean field theory. Additionally, the observed density of states due to magnetic fluctuations is found in the derivative of the differential conductance and is consistent with results from Raman scattering and RIXS. At low temperatures, additional low-energy features were observed, suggesting a change in the dispersion of the collective magnetic excitations, which is consistent with the magnetic susceptibility.

5 pages, 4 figures, submitted to Phys. Rev. B

References in corpus (5)

• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• Twisted Hubbard Model for Sr2IrO4: Magnetism and Possible High Temperature Superconductivity
• Antiferromagnetism and the gap of a Mott insulator: Results from analytic continuation of the self-energy
• Dimensionality controlled Mott transition and correlation effects in single- and bi-layer perovskite iridates
• Observation of Phonon-Assisted Magnon Absorption in Spin-Orbit Coupling Induced Mott Insulator Sr${}_2$IrO${}_4$

Cited by in corpus (11)

• The influence of electron-doping on the ground state of (Sr{1-x}La{x})2IrO4
• Square Lattice Iridates
• Local density of states study of a spin-orbit-coupling induced Mott insulator Sr${}_2$IrO${}_4$
• Evidence of quantum dimer excitations in Sr${}_3$Ir${}_2$O${}_7$
• The Jeff=1/2 antiferromagnet Sr2IrO4: A golden avenue toward new physics and functions
• Doping Evolution of Magnetic Order and Magnetic Excitations in (Sr${}_{1-x}$La${}_x$)${}_3$Ir${}_2$O${}_7$
• Poor electronic screening in lightly doped Mott insulators observed with scanning tunneling microscopy
• Dual gate control of bulk transport and magnetism in the spin-orbit insulator Sr2IrO4
• Pseudogap and electronic structure of electron-doped Sr${}_2$IrO${}_4$
• 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