Robust structural superlubric interfaces under high current density, from understandings to applications

Structural superlubricity (SSL) exhibits significant potential for applications in micro/nanoelectromechanical systems, switches, and sensors, owing to its characteristics of near-zero friction and zero wear. However, the deployment of the more universal 2D/3D SSL interfaces in efficient electronics is severely limited by an insufficient understanding of their electrical stability and failure mechanisms under high current density. In contrast to the Joule-heating-induced interlayer bonding that limits the critical current density in 2D/2D SSL interfaces, we report a fundamentally different failure mechanism for 2D/3D SSL interfaces under high current density: the interfacial Au layer melts and transitions from single-crystalline to polycrystalline state, which drastically increases surface roughness and thus causes a friction surge, severe graphite wear, and the eventual collapse of the SSL state. Notably, under this new failure mechanism, the critical current density of the interface increases by nearly an order of magnitude compared to that of 2D/2D SSL interfaces, exceeding 110 GA/m². Furthermore, we developed a high-power switch prototype that significantly outperforms conventional ones, demonstrating a critical step in translating SSL from principle to practice and paving the way for addressing contact issues in high-power, long-life electronics.