title: Direct 3D mapping of the Fermi surface and Fermi velocity.
abstract: We performed a full mapping of the bulk electronic structure including the Fermi surface and Fermi-velocity distribution vF(kF) of tungsten. The 4D spectral function ρ(EB; k) in the entire bulk Brillouin zone and 6 eV binding-energy (EB) interval was acquired in ∼3 h thanks to a new multidimensional photoemission data-recording technique (combining full-field k-microscopy with time-of-flight parallel energy recording) and the high brilliance of the soft X-rays used. A direct comparison of bulk and surface spectral functions (taken at low photon energies) reveals a time-reversal-invariant surface state in a local bandgap in the (110)-projected bulk band structure. The surface state connects hole and electron pockets that would otherwise be separated by an indirect local bandgap. We confirmed its Dirac-like spin texture by spin-filtered momentum imaging. The measured 4D data array enables extraction of the 3D dispersion of all bands, all energy isosurfaces, electron velocities, hole or electron conductivity, effective mass and inner potential by simple algorithms without approximations. The high-Z bcc metals with large spin-orbit-induced bandgaps are discussed as candidates for topologically non-trivial surface states.
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Medjanik
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Fedchenko
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Chernov
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany.|DESY Photon Science, Notkestraße 85, 22607 Hamburg, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Kutnyakhov
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Ellguth
authors.affiliation: Surface Concept GmbH, Am Sägewerk 23a, 55124 Mainz, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Oelsner
authors.affiliation: Department of Bioengineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: B
authors.initials: B
authors.lastname: Schönhense
authors.affiliation: Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany.
authors.forename: T R F
authors.identifier: 0000-0001-6629-736X
authors.initials: TRF
authors.lastname: Peixoto
authors.affiliation: Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Lutz
authors.affiliation: Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany.
authors.forename: C-H
authors.initials: CH
authors.lastname: Min
authors.affiliation: Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Reinert
authors.affiliation: Laboratorium für Festkörperphysik, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Däster
authors.affiliation: Laboratorium für Festkörperphysik, ETH Zürich, Otto-Stern-Weg 1, 8093 Zürich, Switzerland.
authors.forename: Y
authors.initials: Y
authors.lastname: Acremann
authors.affiliation: DESY Photon Science, Notkestraße 85, 22607 Hamburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Viefhaus
authors.affiliation: DESY Photon Science, Notkestraße 85, 22607 Hamburg, Germany.|Physics Department and Center for Free-Electron Laser Science, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Wurth
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany.
authors.forename: H J
authors.initials: HJ
authors.lastname: Elmers
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, StaudingerWeg 7, 55128 Mainz, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Schönhense