title: Evidence for a small hole pocket in the Fermi surface of underdoped YBa2Cu3Oy.
abstract: In underdoped cuprate superconductors, the Fermi surface undergoes a reconstruction that produces a small electron pocket, but whether there is another, as yet, undetected portion to the Fermi surface is unknown. Establishing the complete topology of the Fermi surface is key to identifying the mechanism responsible for its reconstruction. Here we report evidence for a second Fermi pocket in underdoped YBa2Cu3Oy, detected as a small quantum oscillation frequency in the thermoelectric response and in the c-axis resistance. The field-angle dependence of the frequency shows that it is a distinct Fermi surface, and the normal-state thermopower requires it to be a hole pocket. A Fermi surface consisting of one electron pocket and two hole pockets with the measured areas and masses is consistent with a Fermi-surface reconstruction by the charge-density-wave order observed in YBa2Cu3Oy, provided other parts of the reconstructed Fermi surface are removed by a separate mechanism, possibly the pseudogap.
authors.affiliation: Département de physique &RQMP, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1.
authors.forename: N
authors.initials: N
authors.lastname: Doiron-Leyraud
authors.affiliation: Laboratoire National des Champs Magnétiques Intenses (CNRS, INSA, UJF, UPS), 31400 Toulouse, France.
authors.forename: S
authors.initials: S
authors.lastname: Badoux
authors.affiliation: Département de physique &RQMP, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1.
authors.forename: S
authors.initials: S
authors.lastname: René de Cotret
authors.affiliation: Laboratoire National des Champs Magnétiques Intenses (CNRS, INSA, UJF, UPS), 31400 Toulouse, France.
authors.forename: S
authors.initials: S
authors.lastname: Lepault
authors.affiliation: Laboratoire National des Champs Magnétiques Intenses (CNRS, INSA, UJF, UPS), 31400 Toulouse, France.
authors.forename: D
authors.initials: D
authors.lastname: LeBoeuf
authors.affiliation: Département de physique &RQMP, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1.
authors.forename: F
authors.initials: F
authors.lastname: Laliberté
authors.affiliation: Département de physique &RQMP, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1.
authors.forename: E
authors.initials: E
authors.lastname: Hassinger
authors.affiliation: Department of Physics &Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: B J
authors.initials: BJ
authors.lastname: Ramshaw
authors.affiliation: 1] Department of Physics &Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1 [2] Canadian Institute for Advanced Research, Toronto, Ontario, Canada M5G 1Z8.
authors.forename: D A
authors.initials: DA
authors.lastname: Bonn
authors.affiliation: 1] Department of Physics &Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1 [2] Canadian Institute for Advanced Research, Toronto, Ontario, Canada M5G 1Z8.
authors.forename: W N
authors.initials: WN
authors.lastname: Hardy
authors.affiliation: 1] Department of Physics &Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1 [2] Canadian Institute for Advanced Research, Toronto, Ontario, Canada M5G 1Z8.
authors.forename: R
authors.initials: R
authors.lastname: Liang
authors.affiliation: National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA.
authors.forename: J-H
authors.initials: JH
authors.lastname: Park
authors.affiliation: Laboratoire National des Champs Magnétiques Intenses (CNRS, INSA, UJF, UPS), 31400 Toulouse, France.
authors.forename: D
authors.initials: D
authors.lastname: Vignolles
authors.affiliation: Laboratoire National des Champs Magnétiques Intenses (CNRS, INSA, UJF, UPS), 31400 Toulouse, France.
authors.forename: B
authors.initials: B
authors.lastname: Vignolle
authors.affiliation: 1] Département de physique &RQMP, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1 [2] Canadian Institute for Advanced Research, Toronto, Ontario, Canada M5G 1Z8.
authors.forename: L
authors.initials: L
authors.lastname: Taillefer
authors.affiliation: 1] Laboratoire National des Champs Magnétiques Intenses (CNRS, INSA, UJF, UPS), 31400 Toulouse, France [2] Canadian Institute for Advanced Research, Toronto, Ontario, Canada M5G 1Z8.
authors.forename: C
authors.initials: C
authors.lastname: Proust