Signature of high temperature superconductivity in electron doped Sr2IrO4

TL;DR

This study provides evidence of high temperature superconductivity signatures in electron-doped Sr2IrO4, showing a superconducting gap and transition temperature, with a progression from insulator to metal, similar to cuprate behavior.

Contribution

First direct STM/STS evidence of superconductivity in electron-doped Sr2IrO4, revealing a superconducting gap and transition temperature, highlighting its analogy to cuprates.

Findings

Observation of a 25-30 meV superconducting gap at 0.5-0.6 ML K coverage

Superconducting features vanish around 50 K

Progression from insulator to metal with doping

Abstract

Sr2IrO4 was predicted to be a high temperature superconductor upon electron doping since it highly resembles the cuprates in crystal structure, electronic structure and magnetic coupling constants. Here we report a scanning tunneling microscopy/spectroscopy (STM/STS) study of Sr2IrO4 with surface electron doping by depositing potassium (K) atoms. At the 0.5-0.7 monolayer (ML) K coverage, we observed a sharp, V-shaped gap with about 95% loss of density of state (DOS) at EFand visible coherence peaks. The gap magnitude is 25-30 meV for 0.5-0.6 ML K coverage and it closes around 50 K. These behaviors exhibit clear signature of superconductivity. Furthermore, we found that with increased electron doping, the system gradually evolves from an insulating state to a normal metallic state, via a pseudogap-like state and possible superconducting state. Our data suggest possible high temperature superconductivity in electron doped Sr2IrO4, and its remarkable analogy to the cuprates.