‘Graphene highway’ allows devices to use significantly less energy • Earth.com

Physicists have created a five-lane graphene electron superhighway that could pave the way for ultra-efficient electronics and more. The work concerns a unique form of pencil known as rhombohedral five-layer graphene.

Long Ju is an assistant professor in MIT’s Department of Physics and co-author of the paper. He explains: “This discovery has direct implications for low-power electronic devices because there is no loss of energy during electron propagation, which is not the case with ordinary materials in which electrons are scattered.”

Smooth access for electrons

The phenomenon discovered by the team resembles cars driving on an open highway as opposed to cars driving through neighborhoods.

In ordinary materials, electrons can be stopped or slowed down by other factors, just as nearby cars can be disrupted by suddenly stopping or turning around. However, in rhombohedral five-layer graphene, electrons can move freely.

“We have found a gold mine, and every scoop reveals something new,” says Ju, who is also affiliated with MIT’s Materials Research Laboratory. The material was first discovered two years ago by physicists led by Ju.

The birth of the graphene highway

IN Nanotechnology of nature Last October, in their paper, Ju and colleagues reported the discovery of three important properties arising from rhombohedral graphene.

They showed that this could be topological, allowing electrons to move unimpeded around the edges of the material but not through the center. This resulted in a highway, but required the use of a large magnetic field.

In their current work, the team managed to create a highway without a magnetic field.

Tonghang Han is a physics graduate student at MIT and co-author of the paper. He notes: “We are not the first to discover this general phenomenon, but we did it in a completely different system. Compared to previous systems, ours is simpler and also supports more electron channels.

A highway powered by rhombohedral graphene

Pencil, or graphite, is composed of graphene, a single layer of carbon atoms arranged in a honeycomb structure.

Rhombohedral graphene consists of five layers of graphene arranged in a specific order, overlapping each other.

Ju and colleagues isolated this unique form of graphene thanks to Ju’s novel microscope built at MIT in 2021, which can quickly and relatively inexpensively determine a number of important nanoscale features of the material.

In the current work, the team added a layer of tungsten disulfide (WS2) to the original system.

“The interaction between WS2 and five-layer rhombohedral graphene resulted in a five-lane highway operating at zero magnetic field,” says Ju.

Quantum anomalous Hall effect

The phenomenon that allows electrons to move without resistance at zero magnetic field in rhombohedral graphene is known as the quantum anomalous Hall effect.

This is different from superconductivity, which does the same thing but happens in very different materials.

Ju notes that although superconductors were discovered in the 1910s, it took about 100 years of research to make them work at the higher temperatures necessary for applications.

Similarly, the rhombohedral graphene highway currently operates at a temperature of about 2 Kelvin, or -456 Fahrenheit.

“Raising the temperature will take a lot of effort, but our job as physicists is to provide insight; a different way to become aware of this (phenomenon),” Ju says.

Perseverance and painstaking research pay off

The rhombohedral graphene discoveries were the result of tireless research that did not guarantee success.

Han says: “We tried many recipes over many months, so it was very exciting when we cooled the system to a very low temperature and (a five-lane highway operating at zero magnetic field) just popped up.”

Ju concludes: “It’s very exciting to be the first to discover a phenomenon in a new system, especially in the material we discovered.”

A new era in electron transport

In conclusion, the discovery of the five-lane electron highway in rhombohedral five-layer graphene represents a significant milestone in the field of physics and electronics.

The tireless efforts of Long Ju, Tonghang Han and their colleagues at MIT have opened up new possibilities for ultra-efficient, low-power electronic devices.

Although there is still a long way to go before this technology becomes practical in everyday applications, physicists have laid the foundations for a new era in electron transport.

As we continue to explore the properties of this unique form of graphene, we can expect even more exciting discoveries in the future.

The five-lane graphene-electron superhighway is just the beginning of a journey that could revolutionize the way we think about and design electronic devices.

The full study was published in the journal Science.

—–

Do you like what you read? Subscribe to our newsletter to receive interesting articles, exclusive content and the latest updates.

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–