title: Normal-state nodal electronic structure in underdoped high-Tc copper oxides.
abstract: An outstanding problem in the field of high-transition-temperature (high-Tc) superconductivity is the identification of the normal state out of which superconductivity emerges in the mysterious underdoped regime. The normal state uncomplicated by thermal fluctuations can be studied using applied magnetic fields that are sufficiently strong to suppress long-range superconductivity at low temperatures. Proposals in which the normal ground state is characterized by small Fermi surface pockets that exist in the absence of symmetry breaking have been superseded by models based on the existence of a superlattice that breaks the translational symmetry of the underlying lattice. Recently, a charge superlattice model that positions a small electron-like Fermi pocket in the vicinity of the nodes (where the superconducting gap is minimum) has been proposed as a replacement for the prevalent superlattice models that position the Fermi pocket in the vicinity of the pseudogap at the antinodes (where the superconducting gap is maximum). Although some ingredients of symmetry breaking have been recently revealed by crystallographic studies, their relevance to the electronic structure remains unresolved. Here we report angle-resolved quantum oscillation measurements in the underdoped copper oxide YBa2Cu3O6 + x. These measurements reveal a normal ground state comprising electron-like Fermi surface pockets located in the vicinity of the nodes, and also point to an underlying superlattice structure of low frequency and long wavelength with features in common with the charge order identified recently by complementary spectroscopic techniques.
authors.affiliation: Cavendish Laboratory, Cambridge University, JJ Thomson Avenue, Cambridge CB3 OHE, UK.
authors.forename: Suchitra E
authors.initials: SE
authors.lastname: Sebastian
authors.affiliation: National High Magnetic Field Laboratory, Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87504, USA.
authors.forename: N
authors.initials: N
authors.lastname: Harrison
authors.affiliation: National High Magnetic Field Laboratory, Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87504, USA.
authors.forename: F F
authors.initials: FF
authors.lastname: Balakirev
authors.affiliation: 1] National High Magnetic Field Laboratory, Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87504, USA [2] Department of Physics, Mu'tah University, Mu'tah, Karak 61710, Jordan.
authors.forename: M M
authors.initials: MM
authors.lastname: Altarawneh
authors.affiliation: Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
authors.forename: P A
authors.initials: PA
authors.lastname: Goddard
authors.affiliation: 1] Department of Physics and Astronomy, University of British Columbia, Vancouver V6T 1Z4, Canada [2] Canadian Institute for Advanced Research, Quantum Materials Program, Toronto M5G 1Z8, Canada.
authors.forename: Ruixing
authors.initials: R
authors.lastname: Liang
authors.affiliation: 1] Department of Physics and Astronomy, University of British Columbia, Vancouver V6T 1Z4, Canada [2] Canadian Institute for Advanced Research, Quantum Materials Program, Toronto M5G 1Z8, Canada.
authors.forename: D A
authors.initials: DA
authors.lastname: Bonn
authors.affiliation: 1] Department of Physics and Astronomy, University of British Columbia, Vancouver V6T 1Z4, Canada [2] Canadian Institute for Advanced Research, Quantum Materials Program, Toronto M5G 1Z8, Canada.
authors.forename: W N
authors.initials: WN
authors.lastname: Hardy
authors.affiliation: Cavendish Laboratory, Cambridge University, JJ Thomson Avenue, Cambridge CB3 OHE, UK.
authors.forename: G G
authors.initials: GG
authors.lastname: Lonzarich