Reconstruction of the Bi2Sr2CaCu2O8+δ Fermi surface

The effects of structural supermodulation with the period $\ensuremath{\lambda}\ensuremath{\approx}26$ \AA{} along the $b$ axis of ${\mathrm{Bi}}₂{\mathrm{Sr}}₂{\mathrm{CaCu}}₂{\mathrm{O}}_{8+\ensuremath{\delta}}$ have been observed in photoemission studies from the early days as the presence of ``diffraction replicas'' of the intrinsic electronic structure. Although predicted to affect the electronic structure of the Cu-O plane, the influence of supermodulation potential on Cu-O electrons has never been observed in photoemission. In the present study, we clearly see the effects on the ${\mathrm{Bi}}<sub>2</sub>{\mathrm{Sr}}<sub>2</sub>{\mathrm{CaCu}}<sub>2</sub>{\mathrm{O}}_{8+\ensuremath{\delta}}$ electronic structure; we observe a hybridization of the intrinsic bands with the supermodulation replica bands in the form of avoided crossings and a corresponding reconstruction of the Fermi surface. We estimate the hybridization gap, $2{\mathrm{\ensuremath{\Delta}}}<sub>h</sub>\ensuremath{\sim}25$ meV, in the slightly underdoped samples. The hybridization weakens with doping and the anticrossing can no longer be resolved in strongly overdoped samples. In contrast, the ``shadow'' replica, shifted by $(\ensuremath{\pi},\ensuremath{\pi})$, is found not to hybridize with the original bands within our detection limits.