An international research team led by scientists from the University of Göttingen has confirmed the theory that electrons pass through naturally occurring double-layer graphene without mass in the same way as light.
The experiments, assisted by researchers at the Massachusetts Institute of Technology (MIT) and the National Institute of Materials Science (NIMS), also show that, unlike single layers of graphene, stacked bilayers of graphene can switch from a conducting to an insulating state. The discovery could represent a major breakthrough, removing one of the major obstacles limiting graphene’s wider use.
The attractive properties of 2D graphene
Graphene is a two-dimensional material composed of a single layer of carbon atoms and was first discovered in 2004. The most popular theory, proposed in 2009, suggests that they move without mass, like light, which could explain graphene’s highly conductive properties.
To confirm this idea, the research team developed an experiment involving a stack of multiple layers of graphene. This involves cooling the double-layer graphene to cryogenic temperatures, about 273 degrees below freezing.
Remarkably, the researchers noted that these experiments weren’t even possible in 2009. Fortunately, it’s 2024 and folks at NIMS are able to produce the type of graphene the team needs.
Sure enough, by measuring the electrons’ journey through the enhanced double-layer graphene and working closely with the theory at MIT, they confirmed that they move like particles without any light-like mass.
“We already knew the theory,” explains Professor Thomas Weitz from the School of Physics at the University of Göttingen. However, now we have performed experiments that actually show light-like dispersion of electrons in bilayer graphene.
This is a very exciting time for the whole team.
Research also reveals the insulating state of double-layer graphene
Their research was published in the journal nature communications, researchers explain how graphene’s highly conductive properties have scientists dreaming of using graphene to create faster, more energy-efficient transistors. Unfortunately, a transistor is essentially an electronic switch, just like a light switch in your home, and it must be able to turn on and off. Despite graphene’s compelling electromagnetic properties, it’s not actually insulating, meaning it’s always on.
The researchers said they were surprised to find that double-layer graphene did not have this limitation. Instead, their experiments on electron dispersion in bilayer graphene showed that applying an external electric field can transform the material into an insulating state. In effect, they can switch the material’s conductivity from on to off.
The researchers explain that two layers of graphene in the naturally occurring form of bilayer graphene combine the advantages of two layers of graphene, a structure that supports electrons moving as fast as light as if they had no mass. .
The team acknowledged that their experiments were conducted at extremely cold temperatures in a laboratory setting, rather than at room temperature. However, they believe future research can expand this temperature range enough to make bilayer graphene a viable candidate for creating ultra-efficient transistors and other electronic devices that take advantage of the material’s unique properties.
Dr. Anna Seiler, a postdoctoral researcher at the University of Göttingen and the first author of the paper, said that our work is very much a first step, but it is a crucial step. The next step for the researchers will be to see if double-layer graphene can actually improve transistors or investigate the potential of this effect in other areas of technology.
Christopher Plain is a science fiction novelist and chief science writer for The Report.Follow him and contact him X, Visit plainfiction.com to learn about his books, or email him directly at christopher@thedebrief.org.
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