title: Evidence for a Strong Topological Insulator Phase in ZrTe_{5}.
abstract: The complex electronic properties of ZrTe_{5} have recently stimulated in-depth investigations that assigned this material to either a topological insulator or a 3D Dirac semimetal phase. Here we report a comprehensive experimental and theoretical study of both electronic and structural properties of ZrTe_{5}, revealing that the bulk material is a strong topological insulator (STI). By means of angle-resolved photoelectron spectroscopy, we identify at the top of the valence band both a surface and a bulk state. The dispersion of these bands is well captured by ab initio calculations for the STI case, for the specific interlayer distance measured in our x-ray diffraction study. Furthermore, these findings are supported by scanning tunneling spectroscopy revealing the metallic character of the sample surface, thus confirming the strong topological nature of ZrTe_{5}.
authors.affiliation: Universitá degli Studi di Trieste, Via Alfonso Valerio 2, Trieste 34127, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Manzoni
authors.affiliation: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Gragnaniello
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.|National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: G
authors.initials: G
authors.lastname: Autès
authors.affiliation: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kuhn
authors.affiliation: Universitá degli Studi di Trieste, Via Alfonso Valerio 2, Trieste 34127, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Sterzi
authors.affiliation: Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14, km 163.5, Trieste I-34149, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Cilento
authors.affiliation: Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park - Basovizza, I-34149 Trieste, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Zacchigna
authors.affiliation: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Enenkel
authors.affiliation: Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park - Basovizza, I-34149 Trieste, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Vobornik
authors.affiliation: Institute of Crystallography, CNR, Area Science Park, Strada Statale 14, km 163.5 Trieste I-34149, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Barba
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Bisti
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: Ph
authors.initials: P
authors.lastname: Bugnon
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Magrez
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: V N
authors.initials: VN
authors.lastname: Strocov
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Berger
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.|National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: O V
authors.initials: OV
authors.lastname: Yazyev
authors.affiliation: Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Fonin
authors.affiliation: Universitá degli Studi di Trieste, Via Alfonso Valerio 2, Trieste 34127, Italy.|Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14, km 163.5, Trieste I-34149, Italy.|International Faculty, University of Köln, 50937 Köln, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Parmigiani
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.|Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14, km 163.5, Trieste I-34149, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Crepaldi