Graphene is stronger than steel, harder than diamond and extremely conductive – and it’s only one atom thick. Researchers at Harvard have advanced the frontier on graphene by observing electrons in a metal behaving like a fluid for the first time.
The results flew in the face of everything the researchers knew about metal, revealing exotic black hole and string theory physics in the induced state. “Physics we discovered by studying black holes and string theory, we’re seeing in graphene,” said Andrew Lucas, co author of a study published in the journal Science.
Graphene is hailed as a future wonder material by experts but several challenges need to be overcome before commercial applications can hit the market. Researchers are still trying to understand the basic physics of this unique material. A primary challenge with graphene is that it’s simply hard to make and even harder to maintain a pure sample.
“If you have a material that’s one atom thick, it’s going to be really affected by its environment,” said lead author of the study Jesse Crossno. “If the graphene is on top of something that’s rough and disordered, it’s going to interfere with how the electrons move. It’s really important to create graphene with no interference from its environment.”
To get around this problem, the team improved methods to create ultra-clean graphene and developed a new way to measure its thermal conductivity.
The ultra-clean graphene was created by isolating the one-atom thick graphene sheet between several layers of an electrically insulating perfect transparent crystal, with a similar atomic structure to graphene. The method took years to perfect to create a truly ultra-pure sample of graphene.
With their pure sample in hand, scientists set up a soup of charged particles on the surface of the graphene and observed how the particles flowed. What they saw was completely unexpected – the particles acted not like individual particles but like a fluid, obeying the laws of hydrodynamics.
“This is the first model system of relativistic hydrodynamics in a metal,” said team member Subir Sachdev, a Professor of Physics at Harvard.
Black Holes and other high energy systems are understood by combining theories of hydrodynamics with Einstein’s theories of relativity. The fluid state of charged particles on graphene is a real world way to observe and study the exotic physics that govern high energy phenomena.
The results also foreshadow further innovation in industrial applications and electrical devices. By measuring graphenes thermal conductivity, the team showed it to be extremely efficient at converting thermal energy into electric currents, and vice versa.
Co-author Lucas says, “In principle, with a clean sample of graphene there may be no limit to how good a device you could make.”