High-purity valley-polarized currents induced by bichromatic optical fields in two-dimensional materials

作     者：Wenqing Li Xiaosong Zhu Liang Li Wanzhu He Jie Long Pengfei Lan Peixiang Lu 

作者机构：Wuhan National Laboratory for Optoelectronics and School of Physics Huazhong University of Science and Technology Wuhan 430074 China Hubei Optical Fundamental Research Center Wuhan 430074 China Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan Institute of Technology Wuhan 430205 China 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2025年第111卷第11期

页      面：115406-115406页

核心收录：

基　　金：National Natural Science Foundation of China, NSFC, (12104172, 12374317, 12021004, 12174134) National Natural Science Foundation of China, NSFC National Key Research and Development Program of China, NKRDPC, (2022YFA1604403, 2023YFA1406800) National Key Research and Development Program of China, NKRDPC 

主　　题：Landforms 

摘      要：Producing currents predominantly from a single valley, namely, valley-polarized currents, at optical-cycle timescales is an important aspect of the petahertz valleytronics, yet it remains less developed. This work exhibits the feasibility of achieving this goal using bichromatic optical fields, which allow for the precise control of subcycle electron dynamics. The combined effect of the helical and asymmetric waveforms of the optical fields leads to highly asymmetric excitation at different valleys and displacement of the excited electrons concurrently, thereby inducing valley-polarized currents with high valley purity, on the sub-optical-cycle timescale. Inherently, the purity of the currents built up from the optical approach remains high even for materials with short decoherence time. Moreover, the direction of the currents can be precisely controlled by adjusting the relative phase of the bichromatic components. Our work offers a promising avenue for generating and modulating high-purity valley-polarized currents at the femtosecond timescale, facilitating the development of petahertz valleytronics.