ARPES Study of the Metal-Insulator Transition in Bismuth Cobaltates

TL;DR

This study uses ARPES to investigate how chemical doping influences the electronic structure and metal-insulator transition in bismuth cobaltates, revealing systematic spectral and dispersion changes.

Contribution

It provides new insights into the spectral evolution and band dispersion associated with the metal-insulator transition in bismuth cobaltates through ARPES analysis.

Findings

Spectral weight shifts between coherent and incoherent parts with doping

Emergence of a weakly dispersing state at the Fermi level

Changes in temperature-dependent resistivity correlate with spectral evolution

Abstract

We present an angle-resolved photoemission spectroscopy (ARPES) study of a Mott-Hubbard-type bismuth cobaltate system across a metal-insulator transition. By varying the amount of Pb substitution, and by doping with Sr or Ba cation, a range of insulating to metallic properties is obtained. We observe a systematic change in the spectral weight of the coherent and incoherent parts, accompanied by an energy shift of the incoherent part. The band dispersion also shows the emergence of a weakly dispersing state at the Fermi energy with increasing conductivity. These changes correspond with the changes in the temperature-dependent resistivity behavior. We address the nature of the coherent-incoherent parts in relation to the peak-dip-hump feature seen in cuprates superconductors.