title: Anomalous spectral features of a neutral bilayer graphene.
abstract: Graphene and its bilayer are two-dimensional systems predicted to show exciting many-body effects near the neutrality point. The ideal tool to investigate spectrum reconstruction effects is angle-resolved photoemission spectroscopy (ARPES) as it probes directly the band structure with information about both energy and momentum. Here we reveal, by studying undoped exfoliated bilayer graphene with ARPES, two essential aspects of its many-body physics: the electron-phonon scattering rate has an anisotropic k-dependence and the type of electronic liquid is non-Fermi liquid. The latter behavior is evident from an observed electron-electron scattering rate that scales linearly with energy from 100 meV to 600 meV and that is associated with the proximity of bilayer graphene to a two-dimensional quantum critical point of competing orders.
authors.affiliation: National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu, 30076, Taiwan.
authors.forename: C-M
authors.initials: CM
authors.lastname: Cheng
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.|NanoCore, 4 Engineering Drive 3, National University of Singapore 117576, Singapore.
authors.forename: L F
authors.initials: LF
authors.lastname: Xie
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.|Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, 28 Medical Drive, 117456, Singapore.|Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, Block S14, Level 6, 6 Science Drive 2, 117546, Singapore.
authors.forename: A
authors.initials: A
authors.lastname: Pachoud
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.|Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link 117603, Singapore.|Karlsruhe Institute of Technology (KIT), Network of Excellent Retired Scientists (NES) and Institute of Microstructure Technology (IMT), Postfach 3640, 76021 Karlsruhe, Germany.
authors.forename: H O
authors.initials: HO
authors.lastname: Moser
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.|Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, Block S14, Level 6, 6 Science Drive 2, 117546, Singapore.
authors.forename: W
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.|Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, Block S14, Level 6, 6 Science Drive 2, 117546, Singapore.
authors.forename: A T S
authors.initials: ATS
authors.lastname: Wee
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.|Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, Block S14, Level 6, 6 Science Drive 2, 117546, Singapore.
authors.forename: A H
authors.initials: AH
authors.lastname: Castro Neto
authors.affiliation: National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu, 30076, Taiwan.|Department of Physics, National Tsing Hua University, 101 Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan.
authors.forename: K-D
authors.initials: KD
authors.lastname: Tsuei
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.|NanoCore, 4 Engineering Drive 3, National University of Singapore 117576, Singapore.|Centre for Advanced 2D Materials and Graphene Research Centre, Faculty of Science, National University of Singapore, Block S14, Level 6, 6 Science Drive 2, 117546, Singapore.
authors.forename: B
authors.initials: B
authors.lastname: Özyilmaz