TY  - GEN
A1  - Varykhalov, Andrei
A1  - Freyse, Friedrich
A1  - Aguilera, Irene
A1  - Battiato, Marco
A1  - Krivenkov, Maxim
A1  - Marchenko, Dmitry
A1  - Bihlmayer, Gustav
A1  - Blugel, Stefan
A1  - Rader, Oliver
A1  - Sanchez-Barriga, Jaime
T1  - Effective mass enhancement and ultrafast electron dynamics of Au(111) surface state coupled to a quantum well
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - 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.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1354 
KW  - AG
KW  - films
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-549892
SN  - 1866-8372
IS  - 1
ER  - 
TY  - JOUR
A1  - Varykhalov, Andrei
A1  - Freyse, Friedrich
A1  - Aguilera, Irene
A1  - Battiato, Marco
A1  - Krivenkov, Maxim
A1  - Marchenko, Dmitry
A1  - Bihlmayer, Gustav
A1  - Blugel, Stefan
A1  - Rader, Oliver
A1  - Sanchez-Barriga, Jaime
T1  - Effective mass enhancement and ultrafast electron dynamics of Au(111) surface state coupled to a quantum well
JF  - Physical Review Research
N2  - 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.
KW  - AG
KW  - Flims
Y1  - 2020
U6  - https://doi.org/10.1103/PhysRevResearch.2.013343
SN  - 0031-9007
VL  - 2
IS  - 1
SP  - 1
EP  - 9
PB  - American Physical Society
CY  - Ridge, NY
ER  - 
TY  - JOUR
A1  - Sajedi, Maryam
A1  - Krivenkov, Maxim
A1  - Marchenko, Dmitry
A1  - Sanchez-Barriga, Jaime
A1  - Chandran, Anoop K.
A1  - Varykhalov, Andrei
A1  - Rienks, Emile D. L.
A1  - Aguilera, Irene
A1  - Blügel, Stefan
A1  - Rader, Oliver
T1  - Is there a polaron signature in Angle-Resolved Photoemission of CsPbBr3?
JF  - Physical review letters
N2  - The formation of large polarons has been proposed as reason for the high defect tolerance, low mobility, low charge carrier trapping, and low nonradiative recombination rates of lead halide perovskites. Recently, direct evidence for large-polaron formation has been reported from a 50% effective mass enhancement in angle-resolved photoemission of CsPbBr3 over theory for the orthorhombic structure. We present in-depth band dispersion measurements of CsPbBr3 and GW calculations, which lead to similar effective masses at the valence band maximum of 0.203 1 0.016 m0 in experiment and 0.226 m0 in orthorhombic theory. We argue that the effective mass can be explained solely on the basis of electron-electron correlation and largepolaron formation cannot be concluded from photoemission data.
Y1  - 2022
U6  - https://doi.org/10.1103/PhysRevLett.128.176405
SN  - 0031-9007
SN  - 1079-7114
VL  - 128
IS  - 17
PB  - American Physical Society
CY  - College Park
ER  -