title: Spin Polarization and Attosecond Time Delay in Photoemission from Spin Degenerate States of Solids.
abstract: After photon absorption, electrons from a dispersive band of a solid require a finite time in the photoemission process before being photoemitted as free particles, in line with recent attosecond-resolved photoemission experiments. According to the Eisenbud-Wigner-Smith model, the time delay is due to a phase shift of different transitions that occur in the process. Such a phase shift is also at the origin of the angular dependent spin polarization of the photoelectron beam, observable in spin degenerate systems without angular momentum transfer by the incident photon. We propose a semiquantitative model which permits us to relate spin and time scales in photoemission from condensed matter targets and to better understand spin- and angle-resolved photoemission spectroscopy (SARPES) experiments on spin degenerate systems. We also present the first experimental determination by SARPES of this time delay in a dispersive band, which is found to be greater than 26 as for electrons emitted from the sp-bulk band of the model system Cu(111).
authors.affiliation: Institut de Physique, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.|Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: Mauro
authors.initials: M
authors.lastname: Fanciulli
authors.affiliation: Department of Chemistry, Ludwig Maximillian University, D-81377 Munich, Germany.
authors.forename: Henrieta
authors.initials: H
authors.lastname: Volfová
authors.affiliation: Institut de Physique, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.|Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Muff
authors.affiliation: Department of Chemistry, Ludwig Maximillian University, D-81377 Munich, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Braun
authors.affiliation: Department of Chemistry, Ludwig Maximillian University, D-81377 Munich, Germany.
authors.forename: Hubert
authors.initials: H
authors.lastname: Ebert
authors.affiliation: Department of Chemistry, Ludwig Maximillian University, D-81377 Munich, Germany.|New Technologies-Research Center, University of West Bohemia, CZ-30614 Pilsen, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Minár
authors.affiliation: Faculty of Physics, University of Bielefeld, D-33501 Bielefeld, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Heinzmann
authors.affiliation: Institut de Physique, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.|Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.
authors.forename: J Hugo
authors.initials: JH
authors.lastname: Dil