title: Layer-dependent quantum cooperation of electron and hole states in the anomalous semimetal WTe2.
abstract: The behaviour of electrons and holes in a crystal lattice is a fundamental quantum phenomenon, accounting for a rich variety of material properties. Boosted by the remarkable electronic and physical properties of two-dimensional materials such as graphene and topological insulators, transition metal dichalcogenides have recently received renewed attention. In this context, the anomalous bulk properties of semimetallic WTe2 have attracted considerable interest. Here we report angle- and spin-resolved photoemission spectroscopy of WTe2 single crystals, through which we disentangle the role of W and Te atoms in the formation of the band structure and identify the interplay of charge, spin and orbital degrees of freedom. Supported by first-principles calculations and high-resolution surface topography, we reveal the existence of a layer-dependent behaviour. The balance of electron and hole states is found only when considering at least three Te-W-Te layers, showing that the behaviour of WTe2 is not strictly two dimensional.
authors.affiliation: Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy.|International Centre for Theoretical Physics (ICTP), Strada Costiera 11, I-34100 Trieste, Italy.
authors.forename: Pranab Kumar
authors.initials: PK
authors.lastname: Das
authors.affiliation: Consiglio Nazionale delle Ricerche-CNR-SPIN, I-67100 L'Aquila, Italy.|Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio, I-67100 L'Aquila, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Di Sante
authors.affiliation: Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy.
authors.forename: I
authors.initials: I
authors.lastname: Vobornik
authors.affiliation: Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy.
authors.forename: J
authors.initials: J
authors.lastname: Fujii
authors.affiliation: Hiroshima Synchrotron Radiation Center (HSRC), Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima 739-0046, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Okuda
authors.affiliation: Consiglio Nazionale delle Ricerche-CNR-SPIN, I-67100 L'Aquila, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Bruyer
authors.affiliation: Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: A
authors.initials: A
authors.lastname: Gyenis
authors.affiliation: Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Feldman
authors.affiliation: Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: J
authors.initials: J
authors.lastname: Tao
authors.affiliation: Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Ciancio
authors.affiliation: Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy.|Dipartimento di Fisica, Università di Milano, Via Celoria 16, I-20133 Milano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Rossi
authors.affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: M N
authors.initials: MN
authors.lastname: Ali
authors.affiliation: Consiglio Nazionale delle Ricerche-CNR-SPIN, I-67100 L'Aquila, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Picozzi
authors.affiliation: Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: A
authors.initials: A
authors.lastname: Yadzani
authors.affiliation: Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Panaccione
authors.affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Cava