title: Absence of residual quasiparticle conductivity in the underdoped cuprate YBa2Cu4O8.
abstract: We report measurements of the in-plane thermal conductivity kappa of the stoichiometric underdoped cuprate YBa2Cu4O8 (Y124) below 1 K. kappa(T) is shown to follow a simple phononic T3 dependence at the lowest temperature T for both current directions, with a negligible linear quasiparticle contribution. This observation is in marked contrast with behavior reported in optimally doped cuprates, and implies that extended zero-energy (or low-energy) quasiparticles are absent in Y124.
authors.affiliation: Department of Physics, Loughborough University, Loughborough LE11 3TU, United Kingdom.
authors.forename: N E
authors.initials: NE
authors.lastname: Hussey
authors.forename: S
authors.initials: S
authors.lastname: Nakamae
authors.forename: K
authors.initials: K
authors.lastname: Behnia
authors.forename: H
authors.initials: H
authors.lastname: Takagi
authors.forename: C
authors.initials: C
authors.lastname: Urano
authors.forename: S
authors.initials: S
authors.lastname: Adachi
authors.forename: S
authors.initials: S
authors.lastname: Tajima