Discovery of a New Mechanism of Thermal Transport

Current-carrying nanotubes heat up nearby materials but not themselves, indicating a new path to energy-efficient electronics.

Depiction of the new thermal transport mechanism.
Image courtesy of John Cumings
Depiction of the new thermal transport mechanism: On the left and right are metal contacts to a carbon nanotube in-between. As an electric current flows through the nanotube, the substrate beneath is heated directly (as indicated by the red/yellow color in an electron thermal microscopy image), while at the same time the nanotube itself remains cold (blue).

The Science

Using electron thermal microscopy, heat transport is observed directly from a current-carrying nanotube to a dielectric substrate that demonstrates that the nanotube is not heated.

The Impact

This is an entirely new mechanism of thermal transport, which could bring about a paradigm-shift in thermal management for micro- and nano-electronics.


A new phenomenon has been discovered called “remote Joule heating” in which a carbon nanotube carrying an electric current will heat up a substrate nearby, while itself remaining cold. Carbon nanotubes are a nanoscale material known for its excellent ability to carry electric current with low resistance and without being damaged. A new imaging technique called electron thermal microscopy, capable of imaging the heat dissipation in and around nanoscale test structures, was used by the researchers at the University of Maryland to image where the heat is flowing in the carbon nanotube-substrate structures. From these observations, it was concluded that, while the nanotube remains cold, the insulating substrate heats up, even though it is not carrying any electric current itself. The observation matches predictions from a model where the electrons of the nanotube scatter directly off the phonons in the substrate via a phonon-polariton interaction mechanism. The newly observed phenomenon may allow new architectures to be designed for electronics in which the charge-carrying components, e.g., transistors, can be engineered separately from the heat-dissipating components. The discovery could allow a new generation of computer processor designs, achieving higher-performance computing abilities without the speed limitation of conventional processor designs.


John Cumings
University of Maryland


Department of Energy, Office of Science, Basic Energy Sciences program. One of the authors was supported by the US Nuclear Regulatory Commission under a Faculty Development Grant


Kamal H. Baloch, Norvik Voskanian, Merijntje Bronsgeest, and John Cumings, Remote Joule heating by a carbon nanotube, Nature Nanotechnology, 7(5), 316 (2012). [DOI: 10.1038/NNANO.2012.39]

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