title: Magnetic quantum oscillations in YBa2Cu3O6.61 and YBa2Cu3O6.69 in fields of up to 85 T: patching the hole in the roof of the superconducting dome.
abstract: We measure magnetic quantum oscillations in the underdoped cuprates YBa2Cu3O6+x with x=0.61, 0.69, using fields of up to 85 T. The quantum-oscillation frequencies and effective masses obtained suggest that the Fermi energy in the cuprates has a maximum at hole doping p approximately 0.11-0.12. On either side, the effective mass may diverge, possibly due to phase transitions associated with the T=0 limit of the metal-insulator crossover (low-p side), and the postulated topological transition from small to large Fermi surface close to optimal doping (high p side).
authors.affiliation: National High Magnetic Field Laboratory, Los Alamos National Laboratory, MS-E536, Los Alamos, New Mexico 87545, USA.
authors.forename: John
authors.initials: J
authors.lastname: Singleton
authors.forename: Clarina
authors.initials: C
authors.lastname: de la Cruz
authors.forename: R D
authors.initials: RD
authors.lastname: McDonald
authors.forename: Shiliang
authors.initials: S
authors.lastname: Li
authors.forename: Moaz
authors.initials: M
authors.lastname: Altarawneh
authors.forename: Paul
authors.initials: P
authors.lastname: Goddard
authors.forename: Isabel
authors.initials: I
authors.lastname: Franke
authors.forename: Dwight
authors.initials: D
authors.lastname: Rickel
authors.forename: C H
authors.initials: CH
authors.lastname: Mielke
authors.forename: Xin
authors.initials: X
authors.lastname: Yao
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Dai