title: Observation of Landau levels in potassium-intercalated graphite under a zero magnetic field.
abstract: The charge carriers in graphene are massless Dirac fermions and exhibit a relativistic Landau-level quantization in a magnetic field. Recently, it has been reported that, without any external magnetic field, quantized energy levels have been also observed from strained graphene nanobubbles on a platinum surface, which were attributed to the Landau levels of massless Dirac fermions in graphene formed by a strain-induced pseudomagnetic field. Here we show the generation of the Landau levels of massless Dirac fermions on a partially potassium-intercalated graphite surface without applying external magnetic field. Landau levels of massless Dirac fermions indicate the graphene character in partially potassium-intercalated graphite. The generation of the Landau levels is ascribed to a vector potential induced by the perturbation of nearest-neighbour hopping, which may originate from a strain or a gradient of on-site potentials at the perimeters of potassium-free domains.
authors.affiliation: Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Donghui
authors.initials: D
authors.lastname: Guo
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kondo
authors.forename: Takahiro
authors.initials: T
authors.lastname: Machida
authors.forename: Keigo
authors.initials: K
authors.lastname: Iwatake
authors.forename: Susumu
authors.initials: S
authors.lastname: Okada
authors.forename: Junji
authors.initials: J
authors.lastname: Nakamura
mesh_terms: D006108:Graphite / Q000737:chemistry*; D060526:Magnetic Fields; D011188:Potassium / Q000737:chemistry*
chemical_list: D006108:Graphite; D011188:Potassium