Speaker: Peizhe Tang, School of Materials Science and Engineering, Beihang University

Time: 15:00 p.m., February 21, 2024, GMT+8

Venue: Room w563, Physics building, Peking University

Abstract: 

Interactions between light and matter allow the realization of out-of-equilibrium states in quantum solids and lead to the emergence of new complex correlated states. In the first part of this talk, we systemically demonstrate an unconventional excitonic state and its bound phonon sideband in layered silicon diphosphide (SiP2), in which the bound electron-hole pair is composed of electrons confined within one-dimensional phosphorus-phosphorus chains and holes extended in two-dimensional SiP, layers. Furthermore, in the heterostructure of SiP, with other TMDC materials even without twisting, the moiré pattern can be observed, which strongly renormalizes the electronic structures of TMDC and contributes to a giant anisotropic conductance. In the second part, we report the observation of the Floquet engineering and the light-induced band renormalization in black phosphorus. We will discuss the birth and death for the Floquet states in the experimental conditions. In the last part, we report the long-lived light-driven quasi-stationary geometry could stabilize the topological nature in the material family of HgTe compounds. We show that coherent excitation of the infrared-active phonon mode results in a distortion of the atomic geometry with a lifetime of several picoseconds.

Source: School of Physics, PKU