Joys and Pitfalls of Fermi Surface Mapping in Bi 2 Sr 2 CaCu 2 O 8 + δ Using Angle Resolved Photoemission

On the basis of angle-scanned photoemission data recorded using unpolarized radiation, with high $(E,\mathbf{k})$ resolution, and an extremely dense sampling of $\mathbf{k}$ space, we resolve the current controversy regarding the normal state Fermi surface (FS) in ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$. The true picture is simple, self-consistent, and robust: the FS is holelike, with the form of rounded tubes centered on the corners of the Brillouin zone. Two further types of features are also clearly observed: shadow FSs, which are most likely to be due to short range antiferromagnetic spin correlations, and diffraction replicas of the main FS caused by passage of the photoelectrons through the modulated Bi-O planes.