title: Absence of a loss of in-plane infrared spectral weight in the pseudogap regime of Bi(2)Sr(2)CaCu(2)O(8+delta).
abstract: The ab-plane reflectance of Bi(2)Sr(2)CaCu(2)O(8+delta) (Bi-2212) thin films was measured in the 30-25 000 cm(-1) range for one underdoped ( T(c) = 70 K), and one overdoped sample ( T(c) = 63 K) down to 10 K. We find similar behaviors in the temperature dependence of the normal-state infrared response of both samples. Above T(c), the effective spectral weight, obtained from the integrated conductivity, does not decrease when T decreases, so that no opening of an optical pseudogap is seen. We suggest that these are consequences of the pseudogap opening in the k = (0,pi) direction and of the in-plane infrared conductivity being mostly sensitive to the k = (pi,pi) direction.
authors.affiliation: Laboratoire de Physique du Solide, Ecole Supérieure de Physique et Chimie Industrielles de la Ville de Paris, CNRS UPR 5, 75231 Paris Cedex 5, France.
authors.forename: A F
authors.initials: AF
authors.lastname: Santander-Syro
authors.forename: R P S M
authors.initials: RP
authors.lastname: Lobo
authors.forename: N
authors.initials: N
authors.lastname: Bontemps
authors.forename: Z
authors.initials: Z
authors.lastname: Konstantinovic
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: H
authors.initials: H
authors.lastname: Raffy