Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 14: Electronic Structure of Surfaces: Magnetism and Spin Phenomena II
O 14.7: Vortrag
Montag, 20. März 2017, 16:30–16:45, WIL C107
Spin polarization and attosecond time delay in photoemission from spin-degenerate states of Copper, Graphene and BSCCO — •Mauro Fanciulli1,2, Stefan Muff1,2, Andrew P. Weber1,2, Ulrich Heinzmann3, and Hugo Dil1,2 — 1École Polytechnique Fédérale de Lausanne, Switzerland — 2Paul Scherrer Institut, Villigen, Switzerland — 3University of Bielefeld, Germany
During the photoemission process from spin-degenerate states of solids, the photoelectron beam can present a spin polarization which originates from the phase of the photoelectron wavefunction and can be measured by spin-resolved photoemission spectroscopy. The binding energy dependence of the spin polarization can then be related to an attosecond time delay of the photoemission process via the Eisenbud-Wigner-Smith half-scattering model.
Our study involves three different solid state physics benchmark materials: Cu(111), quasi-free-standing graphene, and the cuprate superconductor BSCCO. Without any time resolution, our photoemission experiments on Cu(111) with full angular, energy and spin resolution show an attosecond time delay of the sp bulk-derived band. In the experimentally more complicated cases of graphene and BSCCO a sizeable spin polarization is still observed and can be related to the phase and time information.
These results open the way for new developments in spin- and time-resolved photoemission theory and experimental setups, and could help in the understandings of the physics of many different systems of interest.