Chiral Charge Density Wave and Backscattering-Immune Orbital Texture in Monolayer 1 T -TiTe 2

作者：Mingqiang Ren, Fang-Jun Cheng, Yufei Zhao, Mingqiang Gu, Qiang-Jun Cheng, Binghai Yan, Qihang Liu, Xu-Cun Ma, Qi-Kun Xue, Can‐Li Song · 发表于：Nano Letters · 年份：2023 · DOI：10.1021/acs.nanolett.3c03692 · 被引用次数：5 · 研究领域：2D Materials and Applications、Topological Materials and Phenomena、Advanced Thermoelectric Materials and Devices

Nontrivial electronic states are attracting intense attention in low-dimensional physics. Though chirality has been identified in charge states with a scalar order parameter, its intertwining with charge density waves (CDW), film thickness, and the impact on the electronic behaviors remain less well understood. Here, using scanning tunneling microscopy, we report a 2 × 2 chiral CDW as well as a strong suppression of the Te-5 p hole-band backscattering in monolayer 1 T -TiTe 2 . These exotic characters vanish in bilayer TiTe 2 in a non-CDW state. Theoretical calculations prove that chirality comes from a helical stacking of the triple- q CDW components and, therefore, can persist at the two-dimensional limit. Furthermore, the chirality renders the Te-5 p bands with an unconventional orbital texture that prohibits electron backscattering. Our study establishes TiTe 2 as a promising playground for manipulating the chiral ground states at the monolayer limit and provides a novel path to engineer electronic properties from an orbital degree.