Ordered Graphite Breaks Superlubricity Rule: Friction Vanishes at Forbidden Angle

Researchers at Tsinghua University's Center for Nano and Micro Mechanics observed near-zero, load-independent friction in graphite at twist angles of 21.8° and 38.2°, where the moiré pattern is fully ordered. The finding contradicts the long-held principle that superlubricity requires incommensurate, disordered contacts.

• Superlubricity observed at twist angles 21.8° and 38.2° in the (2,1) configuration
• Friction does not increase with load — the defining signature of superlubricity
• Potential energy surface corrugation is just 0.4 microelectronvolts per atom
• Small moiré unit cell blocks domain-wall formation that normally causes friction