Physicists at the Massachusetts Institute of Technology have developed a new form of graphene that creates a five-lane electrical highway that enables super-efficient electron movement without loss of energy. This breakthrough in rhombic five-layer graphene can transform low-power electronic devices and operate through the quantum anomalous Hall effect in zero magnetic field.
Physicists at the Massachusetts Institute of Technology and their collaborators have created a five-lane highway for electrons that could enable super-efficient electronics and more. The work, reported recently in a journal ScienceIt is one of several significant discoveries made by the same team last year involving the material, a unique form of graphene.
“This discovery has immediate implications for low-power electronic devices because there is no loss of energy when electrons are emitted, which is not the case in conventional materials where electrons scatter,” says Long Ju, associate professor in the Department of Physics and corresponding author of the paper. Science.
This phenomenon is similar to cars driving on the open highway, as opposed to cars driving in the neighborhood. Other drivers may stop or slow nearby cars that stop or turn suddenly, disrupting smooth operation.
New material: rhombic graphene
The material that forms the basis of this work, known as rhombohedral five-layer graphene, was discovered two years ago by physicists led by Zhu. “We found a vein of gold, and each reference reveals something new,” says Zhu, who also works at MIT’s Materials Research Laboratory.
In the document Nature Nanotechnology Last October, Zhu and his colleagues reported the discovery of three important properties of rhombic graphene. For example, they showed that it could be topological, or allow electrons to move freely around the edge of the material but not through the middle. This led to the creation of a superhighway, but required the use of a large magnetic field tens of thousands of times stronger than Earth’s magnetic field.
Improving graphene’s electron channels
In the current study, the team reports the creation of a superhighway without any magnetic field. Tonghang Han, an MIT graduate student in physics, is a co-author of the paper. “We are not the first to discover this general phenomenon, but we did it with a completely different system. Compared to previous systems, our system is simpler and also supports more electronic channels.” Ju explains: “Other materials can only support one lane of traffic at the edge of the material. “Suddenly we increased that to five.”
Other co-authors who contributed equally to the paper are Zhengguang Lu and Yuxuan Yao. Lu is a postdoctoral researcher in the Materials Research Laboratory. Yao conducted the work as a visiting student at Tsinghua University. Other authors are: Liang Fu, MIT professor of physics; Jixiang Yang and Junseok Seo, both MIT graduate students in physics; Chiho Yun and Fan Zhang from the University of Texas at Dallas; and Kenji Watanabe and Takashi Taniguchi from the National Institute for Materials Science in Japan.
How does it work
Graphite, the main component of pencil, consists of many layers of graphene, a single layer of carbon atoms arranged in hexagons resembling a honeycomb structure. Rhombohedral graphene consists of five graphene layers stacked in a specific overlapping pattern.
Ju and his colleagues isolated rhombic graphene, thanks to a new microscope Ju built at MIT in 2021 that can quickly and relatively cheaply determine several important properties of the material at the nanoscale. The five-layer rhombic-folded graphene is only a few billionths of a meter thick.
In the current study, the team modified the original system by adding a layer of tungsten disulfide (WS).2). “The interaction between WS2 and five-layer rhombic graphene led to the creation of this five-lane highway operating in zero magnetic field,” says Zhu.
Comparison with superconductivity
The phenomenon that the Ju group discovered in rhombohedral graphene, which allows electrons to move without resistance in a zero magnetic field, is known as the quantum anomalous Hall effect. Most people are more familiar with superconductivity, which is a completely different phenomenon that does the same thing but occurs in completely different materials.
Although superconductors were discovered in the 1910s, it took nearly 100 years of research to make the system work at the higher temperatures required for application, Zhu notes. “And the world record is still far below room temperature,” he notes.
Similarly, the rhombic graphene highway now operates at a temperature of about 2 Kelvin, or -456 degrees Fahrenheit. “It takes a lot of effort to raise the temperature, but as physicists, our job is to provide insight; there’s another way to do that.” [феномену]” says Ju.
Results and future prospects
The discoveries regarding rhombic graphene were the result of painstaking research that did not guarantee a result. “We tested many recipes over many months,” says Hahn, “so it was very exciting to cool the system down to a very low temperature and [п’ятисмугова магістраль, що працює в нульовому магнітному полі] I just jumped out.”
“It’s very exciting to be the first to discover a phenomenon in a new system, especially in the material we uncovered,” Ju says.
Source: Port Altele
