Academic Affiliation: University of Stuttgart, Germany

Talk: February 15, 2019

Atomically resolved vibrational spectroscopy and ultrafast dynamics in 2D materials

In this talk, first, I will show the results of tip-enhanced Raman spectroscopy (TERS) on emerging 2D borophene and silicene. The highly enhanced electric field perpendicular to the sample surface makes TERS a selective-modes enhancement behavior. The local structures and vibrational properties at defects, domain walls, and strain areas also could be resolved with sub-nanometer spatial resolution. Second, using ultrafast THz-coupled STM, we studied the ultrafast electron dynamics in the correlated material of 1T-TaS2 at the atomic scale. The pump-probe spectra vary strongly on the scale of one unit cell of the David star. The atomically resolved phonon spectroscopy and THz pump-probe spectroscopy are expected to shed new light on some crucial issues, such as charge density wave states and interface enhanced superconductivity.

(References)
1. Sheng, S.; Ma, R.; Wu, J. B.; Li, W.; Kong, L.; Cong, X.; Cao, D.; Hu, W.; Gou, J.; Luo, J. W.; Cheng, P.; Tan, P. H.; Jiang, Y.; Chen, L.; Wu, K., The Pentagonal Nature of Self-Assembled Silicon Chains and Magic Clusters on Ag(110). Nano Lett. 18, 2937-2942 (2018).
2. Sheng, S.; Wu, J.; Cong, X.; Li, W.; Gou, J.; Zhong, Q.; Cheng, P.; Tan, P.; Chen, L.; Wu, K., Vibrational Properties of a Monolayer Silicene Sheet Studied by Tip-Enhanced Raman Spectroscopy. Phys. Rev. Lett. 119, 196803 (2017).