Emergent One-Dimensional Charge Order at Domain Walls of Competing Charge-Density-Wave Orders

Competing electronic phases can generate emergent states at their nanoscale interfaces that do not exist in the bulk. Direct real-space visualization of such interfacial states, however, remains exclusive. Here, we report an emergent one-dimensional (1D) charge order confined to atomically sharp domain walls between competing charge density wave (CDW) orders in the rare-earth ditelluride GdTe₂. Using low-temperature scanning tunneling microscopy and spectroscopy, we resolve three distinct symmetry-breaking CDWs occupying spatially separated surface nanodomains. Supported by density functional theory, two originate from intrinsic bulk instabilities, while the third arises from surface-induced Fermi surface reconstruction at the non-van der Waals termination. Strikingly, the boundary between bulk- and surface-derived CDWs hosts a short-range, quasi-1D charge modulation and an emergent energy gap, indicating confined electronic states produced by competing orders. These findings establish CDW domain walls as nanoscale electronic interfaces, offering a promising platform for nanoscale CDW-based devices and domain-wall-defined functional architectures.