Probing the coupling between a doublon excitation and the charge-density wave in TaS2 by ultrafast optical spectroscopy

摘要

Recently, the switching between the different charge-ordered phases of1T-TaS2 has been probed by ultrafast techniques, revealing unexpected phenomenasuch as "hidden" metastable states and peculiar photoexcited charge patterns.Here, we apply broadband pump-probe spectroscopy with varying excitation energyto study the ultrafast optical properties of 1T-TaS2 in the visible regime. Byscanning the excitation energy in the near-IR region we unravel the couplingbetween different charge excitations and the low-lying charge-density wavestate. We find that the amplitude mode of the charge-density wave exhibitsstrong coupling to a long-lived doublon state that is photoinduced in thecenter of the star-shaped charge-ordered Ta clusters by the near-IR opticalexcitation.