Constancy of the bilayer splitting as a function of doping in $B{i}_{2}S{r}_{2}CaC{u}_2{O}_{8+\delta }$

Abstract

Using high energy resolution angle resolved photoemission spectroscopy, we have resolved the bilayer splitting effect in a wide range of dopings of the bilayer cuprate $B{i}_{2}S{r}_{2}CaC{u}_2{O}_{8+\delta }$. This bilayer splitting is due to a nonvanishing intracell coupling $t_{\perp }$, and contrary to expectations, it is not reduced in the underdoped materials. This has implications for understanding the increased c-axis confinement in underdoped materials.