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

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 $Γ-\bar{M}-Z$ direction. The data also indicate that there is an asymmetry in the Fermi surface for both the $Γ-\bar{M}-Z$ and perpendicular directions.

APS_Revtex. 28 pages, including 16 figures, available upon request. UW-Madison preprint#3