Dresden 2017 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 6: Ultrafast Phenoma I

HL 6.6: Vortrag

Montag, 20. März 2017, 11:30–11:45, POT 51

Ultrafast Extreme-UV ARPES Study of the Transition-Metal Dichalcogenide MoSe₂ — •Jan Heye Buss¹, Julian Maklar¹, Frederic Joucken¹, Yiming Xu¹, He Wang¹, Changhyun Ko², Sefaattin Tongay², Junqiao Wu², and Robert A. Kaindl¹ — ¹Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, USA — ²Dept. of Materials Science and Engineering, University of California, Berkeley, USA

Semiconducting transition-metal dichalcogenides exhibit intriguing physical properties, including a large spin-orbit splitting, strong Coulomb interactions, and optical access to the valley degree of freedom. Important insight into the fundamental microscopic interactions can be obtained via studies of the momentum-resolved non-equilibrium carrier dynamics. Here, we present time-resolved ARPES investigations of MoSe₂ crystals using high-repetition-rate extreme-UV femtosecond pulses, enabling us to track the electron dynamics within the full Brillouin zone with high sensitivity. After resonantly driving excitons at the K-point, the transient ARPES signals reveal a rapid time evolution governed by inter-valley scattering to the conduction band minimum on a 70-fs time scale. We will discuss the momentum-space dynamics as well as distinct temporal and spectral features that yield first evidence for the observation of excitons via angle-resolved photoemission spectroscopy.