Regensburg 2025 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 22: 2D Materials: Electronic Structure and Exitations I (joint session O/HL/TT)
HL 22.2: Talk
Tuesday, March 18, 2025, 10:45–11:00, H8
Photoemission Time Scale Determination: the Effect of Crystal Dimensionality and Electronic Correlation — •Fei Guo1, Dmitrii Usanov2, Eduardo B. Guedes2, Mauro Fanciulli3, Arnaud Magrez1, Michele Puppin1, and Hugo Dil1,2 — 1Institute of Physics, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland — 2Photon Science Division, Paul Scherrer Institut, CH-5232 Villigen, Switzerland — 3Laboratoire de Physique des Matériaux et Surfaces, CY Cergy Paris Université, Cergy-Pontoise, 95031, France
Spin polarization of photoelectrons from spin-degenerate dispersive initial states originates from the interference of multiple photoemission channels, measuring the spin polarization with spin- and angle-resolved photoemission spectroscopy (SARPES) allows the estimation of the phases of the interfering channels, and hence the Eisenbud-Wigner-Smith (EWS) time delay of photoemission, which is the amount of time required by the photoelectron to evolve into a free particle final state. While not directly measurable for solid-state photoemission, this time scale has been measured for gaseous photoionization, which is generally in the attosecond (10^-18s) range.
We present investigations with multiple materials of different properties, and by comparing with previous studies, we propose a relationship between the EWS time delay, electronic correlation mechanism, and dimensionality.
Keywords: Angle-Resolved Photoemission Spectroscopy; spin-resolved ARPES; photoemission time scale