Deep-Learning Aided Atomic-Scale Observation of Anisotropic Melting of the Charge Density Wave in TaS2.

Charge density wave (CDW) transitions involve intricate coupling between electronic and lattice dynamics, direct visualization of atomic rearrangements during these processes is hindered by experimental limitations. Here, AI-augmented scanning transmission electron microscopy (STEM) combined with differential phase contrast (DPC) imaging is employed to resolve the anisotropic melting dynamics of the nearly commensurate CDW (NC-CDW) phase in 1T-TaS2. By integrating deep learning-based denoising and atomic position analysis, the evolution of interatomic distances and domain wall migration during the NC-to-incommensurate CDW (IC-CDW) transition under controlled electron beam irradiation is directly tracked. The results reveal that melting initiates at domain boundaries, propagating inward with pronounced anisotropy: intralayer melting progresses ≈3.8 times faster than interlayer melting. Concurrent DPC imaging uncovers electric field variations at phase interfaces, attributed to periodic lattice distortion-induced band reconstruction via the Peierls mechanism. These findings establish a methodology for atomic-scale manipulation of CDW states and provide critical insights for designing TaS2-based multifunctional devices with tailored electronic properties.