Coexistence of superconductivity and charge-density-wave in van der Waals layered material NbTe₄

Charge density wave (CDW) and superconductivity (SC) have been captivating topics for decades in the field of condensed matter physics, arising from their interplay and correlations with other interesting quantum states. Domain walls in CDW, superconductors, and other ordered systems play an important role in phase transitions and exotic electronic behaviors. Here, we find ambient-pressure superconductivity in the recently reported CDW material NbTe_4 by both transport measurements and scanning tunneling spectroscopy. Moreover, using atomically resolved scanning tunneling microscopy, we find that the CDW domain walls of superconducting NbTe_4 host unidirectionality, exhibiting anisotropic interactions with the CDW order, specified by Q_\rm CDW vectors of the 2\times 3 bidirectional CDW. This atomic-scale correlation provides insight into the physics of domain walls in condensed matter systems and establishes a possible Q-vector-dependent defect engineering paradigm.