Observation of stick-slip behavior with structural superlubric characteristics.

Stick-slip is typically associated with high friction and wear, whereas superlubricity is characterized by ultralow friction and negligible wear. Can these two seemingly opposite phenomena coexist? Here, we present an experimental observation of stick-slip behavior that exhibits structural superlubric characteristics, in a microscale single-crystalline Au mesa sliding against a single-crystalline graphite substrate. This behavior emerges when the applied sliding velocity falls below a critical threshold. Unlike traditional ones, this observed stick-slip phenomenon originates from the inherently superlubric Au/graphite interface and exhibits key structural superlubric features: near zero coefficient of friction and wear-free long-distance sliding. Theoretical analysis attributes this duality to the distinctive nature of Au/graphite interface: a globally atomically flat incommensurate van der Waals interface, yet locally weakly pinned by discrete point vacancy defects. Bond formation and rupture at these sites underpin the static-dynamic friction asymmetry that drives stick-slip. These findings not only deepen our understanding of stick-slip and structural superlubricity, but also open pathways for stable, long-lasting control of superlubric interfaces in micro/nanoscale actuators and sensors.