title: Energy-dependent enhancement of the electron-coupling spectrum of the underdoped Bi2Sr2CaCu2O(8+δ) superconductor.
abstract: We have determined the electron-coupling spectrum of superconducting Bi2Sr2CaCu2O(8+δ) from high-resolution angle-resolved photoemission spectra by two deconvolution-free robust methods. As hole concentration decreases, the coupling spectral weight at low energies ≲15  meV shows a twofold and nearly band-independent enhancement, while that around ∼65  meV increases moderately, and that in ≳130  meV decreases leading to a crossover of dominant coupling excitation between them. Our results suggest the competition among multiple screening effects, and provide important clues to the source of sufficiently strong low-energy coupling, λ(LE)≈1, in an underdoped system.
authors.affiliation: Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Anzai
authors.forename: A
authors.initials: A
authors.lastname: Ino
authors.forename: T
authors.initials: T
authors.lastname: Kamo
authors.forename: T
authors.initials: T
authors.lastname: Fujita
authors.forename: M
authors.initials: M
authors.lastname: Arita
authors.forename: H
authors.initials: H
authors.lastname: Namatame
authors.forename: M
authors.initials: M
authors.lastname: Taniguchi
authors.forename: A
authors.initials: A
authors.lastname: Fujimori
authors.forename: Z-X
authors.initials: ZX
authors.lastname: Shen
authors.forename: M
authors.initials: M
authors.lastname: Ishikado
authors.forename: S
authors.initials: S
authors.lastname: Uchida