Graphene meets heat waves

March 6, 2015
Heat can propagate as a wave over very long distances in graphene and other 2-D materials. Credit: EPFL/Andrea Cepellotti 2015

EPFL researchers have shed new light on the fundamental mechanisms of heat dissipation in graphene and other two-dimensional materials. They have shown that heat can propagate as a wave over very long distances. This is key information for engineering the electronics of tomorrow.

In the race to miniaturize , researchers are challenged with a major problem: the smaller or the faster your device, the more challenging it is to cool it down. One solution to improve the cooling is to use materials with very , such as graphene, to quickly dissipate and thereby cool down the circuits.

At the moment, however, potential applications are facing a fundamental problem: how does heat propagate inside these sheets of materials that are no more than a few atoms thick?

In a study published in Nature Communications, a team of EPFL researchers has shed new light on the mechanisms of in graphene and other . They have demonstrated that heat propagates in the form of a wave, just like sound in air. This was up to now a very obscure phenomenon observed in few cases at temperatures close to the absolute zero.Their simulations provide a valuable tool for researchers studying graphene, whether to cool down circuits at the nanoscale, or to replace silicon in tomorrow's electronics.

Quasi-Lossless Propagation

If it has been difficult so far to understand the propagation of heat in two-dimensional materials, it is because these sheets behave in unexpected ways compared to their three-dimensional cousins. In fact, they are capable of transferring heat with extremely limited losses, even at .

Generally, heat propagates in a material through the vibration of atoms. These vibrations are are called "phonons", and as heat propagates though a three-dimensional material,, these phonons keep colliding with each other, merging together, or splitting. All these processes can limit the conductivity of heat along the way. Only under extreme conditions, when temperature goes close to the absolute zero (-200 0C or lower), it is possible to observe quasi-lossless .

A wave of quantum heat

The situation is very different in two dimensional materials, as shown by researchers at EPFL. Their work demonstrates that heat can propagate without significant losses in 2D even at room temperature, thanks to the phenomenon of wave-like diffusion, called "second sound". In that case, all phonons march together in unison over very long distances. "Our simulations, based on first-principles physics, have shown that atomically thin sheets of materials behave, even at room temperature, in the same way as three-dimensional materials at extremely low temperatures" says Andrea Cepellotti, the first author of the study. "We can show that the thermal transport is described by waves, not only in but also in other materials that have not been studied yet," explains Cepellotti. "This is an extremely valuable information for engineers, who could exploit the design of future electronic components using some of these novel two-dimensional materials properties."

Explore further: When temperature goes quantum

More information: Nature Communications, … full/ncomms7400.html

Related Stories

When temperature goes quantum

March 6, 2015

A UA-led collaboration of physicists and chemists has discovered that temperature behaves in strange and unexpected ways in graphene, a material that has scientists sizzling with excitement about its potential for new technological ...

Physicists show unlimited heat conduction in graphene

May 13, 2014

Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz and the National University of Singapore have attested that the thermal conductivity of graphene diverges with the size of the samples. This discovery ...

Recommended for you

Art advancing science at the nanoscale

October 18, 2017

Like many other scientists, Don Ingber, M.D., Ph.D., the Founding Director of the Wyss Institute, is concerned that non-scientists have become skeptical and even fearful of his field at a time when technology can offer solutions ...

Chemical treatment improves quantum dot lasers

October 16, 2017

One of the secrets to making tiny laser devices such as opthalmic surgery scalpels work even more efficiently is the use of tiny semiconductor particles, called quantum dots. In new research at Los Alamos National Laboratory's ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.