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Bilayer splitting and coherence effects in optimal and underdoped $Bi2Sr2CaCu2O8+\delta$
Phys. Rev. B, 69 (9): 094515 (марта 2004)
DOI: 10.1103/PhysRevB.69.094515
Аннотация
We have carried out extensive high-resolution angle-resolved photoemission
(ARPES) experiments on Bi2Sr2CaCu2O8+δ samples, covering the entire
doping range from the overdoped to the optimally and underdoped regimes
in the normal state. Our focus is on delineating the doping dependence
of the bilayer splitting which is associated with the intracell coupling
of electrons between the two CuO2 planes. We exploit the photon energy
of 47 eV, where strong ARPES matrix element effects are found to
provide a tremendous enhancement of the antibonding to bonding component
of the bilayer split bands near (π,0), in good agreement with the
predictions of corresponding first-principles simulations. Our detailed
analysis indicates that the size of the bilayer splitting is only
weakly dependent on the doping level, implying that electronic excitations
continue to maintain some degree of coherence even in the underdoped
regime.
