Researchers at the University of California, Los Angeles, led by Professor Yongjie Hu of the Samueli School of Engineering, have reported the discovery of a metallic material whose ability to conduct heat exceeds that of any metal measured to date. The material, known as theta-phase tantalum nitride, exhibits a thermal conductivity close to 1,100 watts per meter-kelvin, nearly three times higher than copper and silver, which have long been considered the upper benchmark for metallic heat transport.
Li, S., Su, C., Qin, Z., Alatas, A., Kunz, M., Yamada, T., Kelly, S. D., Upton, M. H., Gironda, A., Zhao, J., Kalkan, B., Yang, W., Aoki, T., & Hu, Y. (2026). Metallic θ-phase tantalum nitride has a thermal conductivity triple that of copper. Science. https://doi.org/10.1126/science.aeb1142
Professor Yongjie Hu from University of California stated,
“As AI technologies advance rapidly, heat-dissipation demands are pushing conventional metals like copper to their performance limits, and the heavy global reliance on copper in chips and AI accelerators is becoming a critical concern.”
The finding challenges a century-old assumption in thermal physics that metals are fundamentally constrained in how efficiently they can conduct heat. In conventional metals, heat is carried primarily by free electrons, with atomic vibrations, or phonons, playing a secondary role. Interactions between electrons and phonons, as well as phonon-phonon scattering, have traditionally limited thermal conductivity. Copper, with a conductivity of around 400 W/mK, has therefore dominated thermal management applications across electronics, data centers, and industrial systems.
Theta-phase tantalum nitride departs from this conventional behavior. Experimental measurements show that heat moves through the material with far less resistance than expected for a metal. According to the researchers, this is due to unusually weak interactions between electrons and phonons, allowing thermal energy to flow more freely through the crystal lattice. The result is a level of heat transport previously thought unattainable in metallic systems.
The discovery was guided by theoretical predictions suggesting that the atomic structure of theta-phase tantalum nitride could support enhanced thermal transport. In this phase, tantalum and nitrogen atoms form a distinct hexagonal arrangement that alters how electrons and lattice vibrations interact. The UCLA-led team confirmed the material’s performance using a combination of ultrafast optical spectroscopy, synchrotron X-ray scattering, and time-resolved measurements that track how heat spreads over picosecond timescales after laser excitation.
Thermal conductivity is a critical parameter in modern electronics, where increasing power density has made heat removal a central design constraint. As processors, AI accelerators, and power electronics continue to scale, localized hotspots limit operating speed, reliability, and energy efficiency. Copper remains the most widely used heat-spreading material, accounting for a significant share of the global thermal management market, but its performance is approaching practical limits in advanced systems.
The researchers note that theta-phase tantalum nitride could offer an alternative pathway for managing heat in environments where copper is no longer sufficient. Potential applications extend beyond conventional microelectronics to include data center infrastructure, aerospace systems, and emerging platforms such as quantum devices, where precise thermal control is essential.
The work also builds on prior advances from the same research group in high-thermal-conductivity materials. Professor Hu previously led the experimental discovery of boron arsenide, a semiconductor with exceptional thermal properties, and has demonstrated its integration into gallium nitride devices for improved cooling. Together, these results suggest that long-standing assumptions about heat transport limits may need to be revisited across both metallic and semiconducting materials.
While theta-phase tantalum nitride is not immediately ready for widespread commercial deployment, the discovery establishes a new reference point for what is physically achievable in metals. It also provides design principles that could guide the development of future thermal materials, particularly those engineered to suppress electron-phonon scattering.
As electronic systems increasingly depend on effective heat removal rather than raw computational throughput alone, materials that redefine thermal performance may become as important as advances in transistor design. This study indicates that metals, long thought to be well understood, may still hold unexpected opportunities for thermal engineering innovation.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
