Imagine a super thin sheet made of only one layer of atoms, which is less than a millionth of a millimeter thick. This material is called graphene and it’s made from carbon atoms arranged in a unique pattern like a honeycomb. Graphene was first created in 2004 and is considered remarkable due to its extraordinary properties. Even today, scientists are continuing to explore and understand its potential.
Postdoctoral researcher Areg Ghazaryan and Professor Maksym Serbyn, both of whom are affiliated with the Institute of Science and Technology Austria (ISTA), have been conducting research on graphene for several years now. They have collaborated with Dr. Tobias Holder and Professor Erez Berg from the Weizmann Institute of Science in Israel on this latest project. After extensive research, the team has published their findings on the superconducting properties of graphene in a research paper that was recently featured in the scientific journal Physical Review B. Their work has contributed to the ongoing efforts of scientists to understand the unique characteristics of graphene and explore its potential applications in various fields, such as electronics and energy storage.
“Multilayered graphene has many promising qualities ranging from widely tunable band structure and special optical properties to new forms of superconductivity—meaning being able to conduct electrical current without resistance,” Ghazaryan explains.
“In our theoretical model, we are continuing our work on multilayer graphene and are looking at various possible arrangements of different graphene sheets on top of each other. There, we found new possibilities for creating so-called topological superconductivity.” In their study, the researchers simulated on a computer what happens when you stack a few layers of graphene sheets on top of each other in certain ways.
A contest of electron beauty
“It is like a big beauty contest among the different configurations of stacked sheets of graphene to find the best one,” Serbyn adds. “In it, we are looking at how the electrons that move in the multilayer graphene behave.”
The way graphene’s layers are positioned in relation to each other affects the environment of the electrons surrounding the positively charged nuclear cores of the carbon atoms in the honeycomb lattice. The number of layers also plays a role. Electrons have a negative charge and are attracted to the nuclei but repelled by each other. The number and position of layers can alter the way the electrons interact, creating different properties and behaviors in the material. This is why understanding graphene’s structure is important for studying its potential applications.
“We started by investigating realistic models considering just a single electron interacting with the nuclei of the graphene. Once we found a promising approach, we added the more complicated interactions between many electrons,” Ghazaryan explains. With this approach, the researchers confirmed the occurrence of the exotic form of topological superconductivity.
Looking for nature’s feedback
This kind of theoretical research lays the foundations for future experiments that will create the simulated graphene systems in a laboratory to see if they really behave as predicted. “Our work helps the experimentalists to design new setups without having to try out every configuration of graphene layers,” Ghazaryan says. “Now, theoretical research will continue while experiments will give us feedback from nature.”
While graphene has slowly found applications in research and technologies—for example as carbon nanotubes—its potential as a topological superconductor for electricity is just starting to be understood. Serbyn adds, “We hope to one day be able to fully describe this kind of material on a quantum mechanical level, both for the inherent value of scientific inquiry into the fundamental characteristics of matter and the many potential applications of graphene.”
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