UCLA engineers discover the most heat-conductive metal ever measured

Theta-phase tantalum nitride conducts heat nearly three times better than copper

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Why it matters: For more than a century, copper and silver have set the standard for thermal conductivity in metals. A new study by UCLA engineers and their collaborators challenges that assumption, introducing a metallic compound that conducts heat nearly three times more efficiently than either benchmark.

The research identifies metallic theta-phase tantalum nitride (TaN₍θ₎) as the fastest heat-conducting metal ever measured. Led by Yongjie Hu of UCLA's Samueli School of Engineering, the team reports that the material exhibits a thermal conductivity of roughly 1,100 watts per meter-kelvin – setting a new record in the physics of heat transport. By comparison, copper, the most widely used commercial heat conductor, measures around 400 W/mK, while silver reaches similar levels under ideal conditions.

This leap in performance comes at a critical moment, as high-power processors, graphics accelerators, and artificial intelligence chips face increasing challenges in heat dissipation. Industry-standard copper heat sinks account for roughly one-third of the global thermal management market, but their efficiency ceiling has become a technological bottleneck. As computing workloads and energy densities continue to climb, cooling has emerged as a defining constraint for both hardware design and energy efficiency.

A sequence showing how thermal energy, carried by electrons, spreads through theta-phase tantalum nitride after the metallic material is struck by a pulse of light, from 0.1 to 10 picoseconds.

Hu's research group discovered that the theta-phase variant of tantalum nitride behaves differently from ordinary metals at the atomic scale. Its structure arranges tantalum and nitrogen atoms in a hexagonal lattice, producing unusually weak interactions between electrons and lattice vibrations, known as phonons.

Because electron – phonon and phonon – phonon collisions typically limit a metal's ability to conduct heat, the reduced interactions in theta-phase TaN₍θ₎ allow thermal energy to travel with minimal resistance.

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Experimental data were obtained using advanced synchrotron-based X-ray scattering and ultrafast optical spectroscopy, confirming that the compound channels heat with unprecedented efficiency.

The findings suggest that metallic heat conduction can surpass traditional theoretical limits – a result that could influence the design of materials for high-performance electronics, aerospace systems, and even quantum devices that demand near-perfect thermal stability.

The implications extend beyond theoretical physics. As AI accelerator chips push power densities to new extremes and global computing demand strains copper's physical limits, materials such as theta-phase tantalum nitride could enable more compact, cooler-running architectures. Hu describes the compound as a potentially "fundamentally new and superior alternative" for next-generation thermal management.

Hu's lab has spent nearly a decade at the forefront of thermal materials research. The group previously discovered boron arsenide, a semiconductor with record-high heat conductivity, and later integrated it into gallium nitride devices for chip cooling. With theta-phase TaN₍θ₎, their latest finding adds a metallic counterpart that could complement – or even outperform – many semiconductor-based approaches.