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.