Observation of a van Hove Singularity in $Bi_{2}Sr_{2}Ca_{1}Cu_{2}O_{8+x}$ with Angle Resolved Photoemission

TL;DR

This study uses high-resolution angle-resolved photoemission to identify a van Hove singularity in the normal state of overdoped Bi-2212, revealing an extended saddle point and Fermi surface asymmetry.

Contribution

It provides the first direct observation of a van Hove singularity in Bi-2212 using ARPES, highlighting its role in the electronic structure of this cuprate superconductor.

Findings

Extended saddle point singularity in the density of states

Asymmetry in the Fermi surface observed

Identification of van Hove singularity along specific momentum directions

Abstract

We have performed high energy resolution angle-resolved photoemission studies of the normal state band structure of oxygen overdoped $Bi_{2}Sr_{2}Ca_{1}Cu_{2}O_{8+x}$. We find that there is an extended saddle point singularity in the density of states along $\Gamma-\bar{M}-Z$ direction. The data also indicate that there is an asymmetry in the Fermi surface for both the $\Gamma-\bar{M}-Z$ and perpendicular directions.