Ultrafast manipulation of collective modes via chiral fermions in a charge density wave Weyl semimetal

Dr. Jingbo Qi, Mr. Zhengxing Wei
University of Electronic Science and Technology of China, Chengdu, China


Charge density wave (CDW) is widely present in various quantum materials, where investigation and control of its associated collective modes have been a subject of great interest. Here, the terahertz (THz) emission spectroscopy has been used to study the collective excitations in the typical quasi-one-dimensional CDW Weyl semimetal (TaSe4)2I. Upon excitation of femtosecond optical pulses, we observe broadband THz radiation including the contribution from the ultrafast photocurrent and multiple collective modes related to CDW at low temperature. We discover that properties of the collective modes can be controlled by tuning the circular polarization state of the incident light. Our findings have significant implications for manipulating CDW, provide novel insights into control of charge ordering parameters in quantum materials.