title: Imaging Cyclotron Orbits of Electrons in Graphene.
abstract: Electrons in graphene can travel for several microns without scattering at low temperatures, and their motion becomes ballistic, following classical trajectories. When a magnetic field B is applied perpendicular to the plane, electrons follow cyclotron orbits. Magnetic focusing occurs when electrons injected from one narrow contact focus onto a second contact located an integer number of cyclotron diameters away. By tuning the magnetic field B and electron density n in the graphene layer, we observe magnetic focusing peaks. We use a cooled scanning gate microscope to image cyclotron trajectories in graphene at 4.2 K. The tip creates a local change in density that casts a shadow by deflecting electrons flowing nearby; an image of flow can be obtained by measuring the transmission between contacts as the tip is raster scanned across the sample. On the first magnetic focusing peak, we image a cyclotron orbit that extends from one contact to the other. In addition, we study the geometry of orbits deflected into the second point contact by the tip.
authors: School of Engineering and Applied Sciences and Department of Physics, Harvard University , Cambridge, Massachusetts 02138 United States.
authors: Sagar
authors: S
authors: Bhandari
authors: School of Engineering and Applied Sciences and Department of Physics, Harvard University , Cambridge, Massachusetts 02138 United States.
authors: Gil-Ho
authors: GH
authors: Lee
authors: School of Engineering and Applied Sciences and Department of Physics, Harvard University , Cambridge, Massachusetts 02138 United States.
authors: Anna
authors: A
authors: Klales
authors: National Institute for Materials Science , 1-1 Namiki, Tsukuba, 305-0044, Japan.
authors: Kenji
authors: K
authors: Watanabe
authors: National Institute for Materials Science , 1-1 Namiki, Tsukuba, 305-0044, Japan.
authors: Takashi
authors: T
authors: Taniguchi
authors: School of Engineering and Applied Sciences and Department of Physics, Harvard University , Cambridge, Massachusetts 02138 United States.
authors: Eric
authors: E
authors: Heller
authors: School of Engineering and Applied Sciences and Department of Physics, Harvard University , Cambridge, Massachusetts 02138 United States.
authors: Philip
authors: P
authors: Kim
authors: School of Engineering and Applied Sciences and Department of Physics, Harvard University , Cambridge, Massachusetts 02138 United States.
authors: Robert M
authors: RM
authors: Westervelt
keywords: Graphene; image cyclotron orbits; magnetic focusing; scanning gate microscope