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Title: Effective mass enhancement and ultrafast electron dynamics of Au(111) surface state coupled to a quantum well
Authors: Varykhalov, A.
Freyse, F.
Aguilera, I.
Battiato, Marco
Krivenkov, M.
Marchenko, D.
Bihlmayer, G.
Blügel, S.
Rader, O.
Sánchez-Barriga, J.
Keywords: Science::Physics
Issue Date: 2020
Source: Varykhalov, A., Freyse, F., Aguilera, I., Battiato, M., Krivenkov, M., Marchenko, D., Bihlmayer, G., Blügel, S., Rader, O. & Sánchez-Barriga, J. (2020). Effective mass enhancement and ultrafast electron dynamics of Au(111) surface state coupled to a quantum well. Physical Review Research, 2(1), 013343-1-013343-9.
Project: NAP-SUG
Journal: Physical Review Research
Abstract: We show that, although the equilibrium band dispersion of the Shockley-type surface state of two-dimensional Au(111) quantum films grown on W(110) does not deviate from the expected free-electron-like behavior, its nonequilibrium energy-momentum dispersion probed by time- and angle-resolved photoemission exhibits a remarkable kink above the Fermi level due to a significant enhancement of the effective mass. The kink is pronounced for certain thicknesses of the Au quantum well and vanishes in the very thin limit. We identify the kink as induced by the coupling between the Au(111) surface state and emergent quantum-well states which probe directly the buried gold-tungsten interface. The signatures of the coupling are further revealed by our time-resolved measurements which show that surface state and quantum-well states thermalize together behaving as dynamically locked electron populations. In particular, relaxation of hot carriers following laser excitation is similar for both surface state and quantum-well states and much slower than expected for a bulk metallic system. The influence of quantum confinement on the interplay between elementary scattering processes of the electrons at the surface and ultrafast carrier transport in the direction perpendicular to the surface is shown to be the reason for the slow electron dynamics.
ISSN: 2643-1564
DOI: 10.1103/PhysRevResearch.2.013343
Schools: School of Physical and Mathematical Sciences 
Rights: © 2020 The Authors. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the authors and the published article’s title, journal citation, and DOI.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SPMS Journal Articles

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