TY  - JOUR
AU  - Clark, Oliver J.
AU  - Freyse, Friedrich
AU  - Aguilera, Irene
AU  - Frolov, Alexander S.
AU  - Ionov, Andrey M.
AU  - Bozhko, Sergey I.
AU  - Yashina, Lada V.
AU  - Sánchez-Barriga, Jaime
TI  - Observation of a giant mass enhancement in the ultrafast electron dynamics of a topological semimetal
JO  - Communications Physics
VL  - 4
IS  - 1
SN  - 2399-3650
CY  - London
PB  - Springer Nature
M1  - FZJ-2021-03547
SP  - 165
PY  - 2021
AB  - Topological phases of matter offer exciting possibilities to realize lossless charge and spin information transport on ultrafast time scales. However, this requires detailed knowledge of their nonequilibrium properties. Here, we employ time-, spin- and angle-resolved photoemission to investigate the ultrafast response of the Sb(111) spin-polarized surface state to femtosecond-laser excitation. The surface state exhibits a giant mass enhancement which is observed as a kink structure in its energy-momentum dispersion above the Fermi level. The kink structure, originating from the direct coupling of the surface state to the bulk continuum, is characterized by an abrupt change in the group velocity by ~70%, in agreement with our GW-based band structure calculations. Our observation of this connectivity in the transiently occupied band structure enables the unambiguous experimental verification of the topological nature of the surface state. The influence of bulk-surface coupling is further confirmed by our measurements of the electron dynamics, which show that bulk and surface states behave as a single thermalizing electronic population with distinct contributions from low-k electron-electron and high-k electron-phonon scatterings. These findings are important for future applications of topological semimetals and their excitations in ultrafast spintronics.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000675343600001
DO  - DOI:10.1038/s42005-021-00657-6
UR  - https://juser.fz-juelich.de/record/896714
ER  -