Femtosecond to picosecond transient effects in WSe ₂ observed by pump-probe angle-resolved photoemission spectroscopy.

ABSTRACT: Time-dependent responses of materials to an ultrashort optical pulse carry valuable information about the electronic and lattice dynamics; this research area has been widely studied on novel two-dimensional materials such as graphene, transition metal dichalcogenides (TMDs) and topological insulators (TIs). We report herein a time-resolved and angle-resolved photoemission spectroscopy (TRARPES) study of WSe₂, a layered semiconductor of interest for valley electronics. The results for below-gap optical pumping reveal energy-gain and -loss Floquet replica valence bands that appear instantaneously in concert with the pump pulse. Energy shift, broadening, and complex intensity variation and oscillation at twice the phonon frequency for the valence bands are observed at time scales r

SUBMITTER: Liu RY 

PROVIDER: S-EPMC5700159 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature