title: Gate-tuned normal and superconducting transport at the surface of a topological insulator.
abstract: Three-dimensional topological insulators are characterized by the presence of a bandgap in their bulk and gapless Dirac fermions at their surfaces. New physical phenomena originating from the presence of the Dirac fermions are predicted to occur, and to be experimentally accessible via transport measurements in suitably designed electronic devices. Here we study transport through superconducting junctions fabricated on thin Bi(2)Se(3) single crystals, equipped with a gate electrode. In the presence of perpendicular magnetic field B, sweeping the gate voltage enables us to observe the filling of the Dirac fermion Landau levels, whose character evolves continuously from electron- to hole-like. When B=0, a supercurrent appears, whose magnitude can be gate tuned, and is minimum at the charge neutrality point determined from the Landau level filling. Our results demonstrate how gated nano-electronic devices give control over normal and superconducting transport of Dirac fermions at an individual surface of a three-dimensional topological insulators.
authors.affiliation: Département de Physique de la Matière Condensée, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Sacépé
authors.forename: Jeroen B
authors.initials: JB
authors.lastname: Oostinga
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Alberto
authors.initials: A
authors.lastname: Ubaldini
authors.forename: Nuno J G
authors.initials: NJ
authors.lastname: Couto
authors.forename: Enrico
authors.initials: E
authors.lastname: Giannini
authors.forename: Alberto F
authors.initials: AF
authors.lastname: Morpurgo
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D003460:Crystallization; D004566:Electrodes; D004581:Electronics / Q000379:methods*; D004583:Electrons; D004738:Engineering / Q000379:methods*; D006108:Graphite / Q000737:chemistry; D060526:Magnetic Fields; D049329:Nanostructures / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D012643:Selenium / Q000737:chemistry*; D012666:Semiconductors; D013499:Surface Properties
chemical_list: D006108:Graphite; D012643:Selenium; D001729:Bismuth