Atomic-Scale Visualization of Chiral Charge Density Wave States and Their Reversible Transition

TL;DR

This study visualizes and characterizes the reversible chiral charge density wave transition at atomic resolution in a 2D material, revealing dynamic intermediate states and potential for nanoscale device applications.

Contribution

It provides the first atomic-scale visualization of reversible chirality switching in a 2D charge density wave system using STM.

Findings

Chirality can be switched reversibly with an electric field.

Atomic lattice remains continuous during chirality transition.

Multiple intermediate states are observed during the transition.

Abstract

Chirality is essential for various amazing phenomena in life and matter. However,chirality and its switching in electronic superlattices, such as charge density wave(CDW) arrays, remain elusive. In this study, we characterize the chirality transition with atom-resolution imaging in a single-layer NbSe2 CDW pattern by technique of scanning tunneling microscopy. The atomic lattice of the CDW array is found continuous and intact although its chirality is switched. Several intermediate states are tracked by time-resolved imaging, revealing the fast and dynamic chirality transition. Importantly, the switching is reversibly realized with an external electric-field. Our findings unveil the delicate transition process of chiral CDW array in a 2D crystal down to the atomic scale and may be applicable for future nanoscale devices.