Abstract Metallic materials are critical in integrated circuits as they not only deliver power but also dissipate heat. However, their performance is constrained as metals’ thermal conductivity is capped with a value of about 400 W m-1 K-1. Here, we shatter this long-standing ceiling by high-pressure synthesis of the metallic hexagonal tantalum mononitride (θ-TaN) single crystal with ultrahigh thermal conductivity. The θ-TaN single crystal exhibits a room-temperature thermal conductivity of 502 W m-1 K-1, exceeding the conventional upper limit for metallic thermal conductors, despite the presence of a substantial concentration of nitrogen vacancies. Our findings identify a clear pathway for further enhancing the thermal conductivity through minimizing vacancy concentration in θ-TaN. This work establishes θ-TaN as a highly promising candidate for advanced thermal management applications and introduces a new approach for designing metallic conductors to surpass conventional limits.
Liu et al. (2026) studied this question.