Transfer of spectral weight across the gap of Sr2IrO4 induced by La doping

TL;DR

This study uses ARPES to investigate how doping with La or Rh alters the electronic structure of Sr2IrO4, revealing spectral weight transfer across the gap and an anisotropic gap of 0.7 eV, with implications for understanding correlated electron systems.

Contribution

It provides new insights into the spectral weight transfer and gap evolution in Sr2IrO4 upon doping, highlighting the anisotropic nature of the gap and the persistence of small quasiparticle weight.

Findings

Doped carriers occupy states at the gap edges.

The gap reduces with increased doping.

Spectral weight transfers across the gap despite low quasiparticle weight.

Abstract

We study with Angle Resolved PhotoElectron Spectroscopy (ARPES) the evolution of the electronic structure of Sr2IrO4, when holes or electrons are introduced, through Rh or La substitutions. At low dopings, the added carriers occupy the first available states, at bottom or top of the gap, revealing an anisotropic gap of 0.7eV in good agreement with STM measurements. At further doping, we observe a reduction of the gap and a transfer of spectral weight across the gap, although the quasiparticle weight remains very small. We discuss the origin of the in-gap spectral weight as a local distribution of gap values.