title: Fermi states and anisotropy of Brillouin zone scattering in the decagonal Al-Ni-Co quasicrystal.
abstract: Quasicrystals (QCs) are intermetallic alloys that have excellent long-range order but lack translational symmetry in at least one dimension. The valence band electronic structure near the Fermi energy EF in such materials is of special interest since it has a direct relation to their unusual physical properties. However, the Fermi surface (FS) topology as well as the mechanism of QC structure stabilization are still under debate. Here we report the first observation of the three-dimensional FS and valence band dispersions near EF in decagonal Al70Ni20Co10 (d-AlNiCo) QCs using soft X-ray angle-resolved photoemission spectroscopy. We show that the FS, formed by dispersive Al sp-states, has a multicomponent character due to a large contribution from high-order bands. Moreover, we discover that the magnitude of the gap at the FS related to the interaction with Brillouin zone boundary (Hume-Rothery gap) critically differs for the periodic and quasiperiodic directions.
authors.affiliation: Department for Synchrotron Radiation and Nanotechnology (SYN), Swiss Light Source, Paul Scherrer Institute, Villigen CH-5232, Switzerland.
authors.forename: V A
authors.initials: VA
authors.lastname: Rogalev
authors.affiliation: Department of Advanced Materials and Surfaces, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf CH-8600, Switzerland.
authors.forename: O
authors.initials: O
authors.lastname: Gröning
authors.affiliation: Department of Advanced Materials and Surfaces, EMPA, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf CH-8600, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Widmer
authors.affiliation: Department for Synchrotron Radiation and Nanotechnology (SYN), Swiss Light Source, Paul Scherrer Institute, Villigen CH-5232, Switzerland.|Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
authors.forename: J H
authors.initials: JH
authors.lastname: Dil
authors.affiliation: Department for Synchrotron Radiation and Nanotechnology (SYN), Swiss Light Source, Paul Scherrer Institute, Villigen CH-5232, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Bisti
authors.affiliation: Department for Synchrotron Radiation and Nanotechnology (SYN), Swiss Light Source, Paul Scherrer Institute, Villigen CH-5232, Switzerland.|National Research Center Kurchatov Institute, Akademika Kurchatova Square 1, Moscow 123182, Russia.
authors.forename: L L
authors.initials: LL
authors.lastname: Lev
authors.affiliation: Department for Synchrotron Radiation and Nanotechnology (SYN), Swiss Light Source, Paul Scherrer Institute, Villigen CH-5232, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Schmitt
authors.affiliation: Department for Synchrotron Radiation and Nanotechnology (SYN), Swiss Light Source, Paul Scherrer Institute, Villigen CH-5232, Switzerland.
authors.forename: V N
authors.initials: VN
authors.lastname: Strocov