title: Negative quantum capacitance induced by midgap states in single-layer graphene.
abstract: We demonstrate that single-layer graphene (SLG) decorated with a high density of Ag adatoms displays the unconventional phenomenon of negative quantum capacitance. The Ag adatoms act as resonant impurities and form nearly dispersionless resonant impurity bands near the charge neutrality point (CNP). Resonant impurities quench the kinetic energy and drive the electrons to the Coulomb energy dominated regime with negative compressibility. In the absence of a magnetic field, negative quantum capacitance is observed near the CNP. In the quantum Hall regime, negative quantum capacitance behavior at several Landau level positions is displayed, which is associated with the quenching of kinetic energy by the formation of Landau levels. The negative quantum capacitance effect near the CNP is further enhanced in the presence of Landau levels due to the magnetic-field-enhanced Coulomb interactions.
authors.affiliation: Department of Physics and the William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Zhu
authors.forename: Chao
authors.initials: C
authors.lastname: Zhu
authors.forename: Zefei
authors.initials: Z
authors.lastname: Wu
authors.forename: Yu
authors.initials: Y
authors.lastname: Han
authors.forename: Mingwei
authors.initials: M
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Yuheng
authors.initials: Y
authors.lastname: He
authors.forename: Wei
authors.initials: W
authors.lastname: Xiong
authors.forename: Kam Tuen
authors.initials: KT
authors.lastname: Law
authors.forename: Dangsheng
authors.initials: D
authors.lastname: Su
authors.forename: Ning
authors.initials: N
authors.lastname: Wang