Anomalous High-Energy Waterfall-Like Electronic Structure in 5 d Transition Metal Oxide Sr2IrO4 with a Strong Spin-Orbit Coupling

Abstract

The low energy electronic structure of Sr2IrO4 has been well studied and understood in terms of an effective Jeff = 1/2 Mott insulator model. However, little work has been done in studying its high energy electronic behaviors. Here we report a new observation of the anomalous high energy electronic structure in Sr2IrO4. By taking high-resolution angle-resolved photoemission measurements on Sr2IrO4 over a wide energy range, we have revealed for the first time that the high energy electronic structures show unusual nearly-vertical bands that extend over a large energy range. Such anomalous high energy behaviors resemble the high energy waterfall features observed in the cuprate superconductors. While strong electron correlation plays an important role in producing high energy waterfall features in the cuprate superconductors, the revelation of the high energy anomalies in Sr2IrO4, which exhibits strong spin-orbit coupling and a moderate electron correlation, points to an unknown and novel route in generating exotic electronic excitations.

Spectral functions of Sr2IrO4: theory versus experiment

“…According to ARPES measurements of the magnetic phase, the lowest energy excitations disperse up to the X point and never cross the Fermi level. This spectrum is qualitatively similar to the one measured below T N in previous works [2,25], demonstrating that spectral properties are largely insensitive to the presence [30]. The high-symmetry points of the Brillouin zone are indicated by blue points.…”

“…9, where one sees that the dispersion of Ref. [25] is located at the X point at ∼ 0.1eV www.nature.com/scientificreports/ that has been reached is Sr 2 IrO 4 being a typical system where the Mott-and slater-type behaviors coexist. In addition, Sr 2 IrO 4 has attracted much attention because it exhibits a number of similarities to the parent compound La 2 CuO 4 of high temperature cuprate superconductors in the crystal structure, electronic structure, magnetic structure, and even possible high temperature superconductivity that is predicted in doped Sr 2 IrO 4 23,24 .…”

“…Using angle-resolved photoemission spectroscopy to investigate pure Sr 2 IrO 4 is limited to moderate temperatures due to surface charging effects that prevent an investigation of the sample at very small temperatures. Nevertheless, spectra for temperatures down to T = 20K have been measured [25], which is deep in the antiferromagnetic phase.…”

“…In addition, Sr 2 IrO 4 has attracted much attention because it exhibits a number of similarities to the parent compound La 2 CuO 4 of high temperature cuprate superconductors in the crystal structure, electronic structure, magnetic structure, and even possible high temperature superconductivity that is predicted in doped Sr 2 IrO 4 23,24 . Angle-resolved photoemission spectroscopy (ARPES) is a powerful tool to directly probe the low energy electronic structures of solid materials 25 . While the ARPES results on Sr 2 IrO 4 and related compounds within a relatively narrow energy window agree with the J eff = 1/2 Mott insulator model 7,[13][14][15]18 , little work has been done in studying its high energy electronic behaviors.…”

Structure, magnetism, and transport properties for Ca doping in Sr2IrO4

“…Recently, theoretical and experimental researches are carried out in doped Sr 2 IrO 4 . [9][10][11][12][13][14][15] Most work are about La 3+ or K + substitution for Sr 2+ . 7,[16][17][18] However, both dopants will bring carrier doping.…”