Scientists at the Massachusetts Institute of Technology have made a discovery worthy of J.K. Rowling’s novels. They turned this ultra-thin layer of carbon material into three functioning electronic devices. Typically, such devices are created using more materials that require additional multi-stage preparation. The invention of MIT specialists solves this problem.
The result of the work of scientists from Massachusetts can become the basis for the creation of a new generation of quantum electronic devices capable of conducting electricity without resistance. The results of the study were published on May 3 in the journal Nature Technology.
“In our study, we demonstrated the work of graphene two atomic layers thick, rotated to each other at an angle of 1.1 °. Graphene has proven to be the most versatile of all superconducting materials. Thanks to him, we managed to create several electronic devices on the basis of one platform. This allowed us to study in more detail the properties of superconductivity, which can only be found in two dimensions, ”- said Pablo Jarillo-Herrero, professor of physics at the Massachusetts Institute of Technology.
At a special angle
The new magical material is based on graphene. Graphene is made up of a single layer of carbon atoms that looks like a honeycomb structure.
Graphene was discovered only about 17 years ago. The material has a lot of interesting properties! For example, it is transparent, flexible and more durable than diamond. It also conducts heat and electricity better than most other materials.
In 2018, the Jarillo-Herrero team made an incredible discovery by placing two layers of graphene on top of each other and slightly changing the angle (the magic 1.1 °) of one of them. The resulting “system” made it possible to transform graphene into both a superconductor and an insulator. The state of the material depends on the number of electrons in the electric field acting on the graphene. In fact, scientists were able to “tune” graphene, radically changing its state by increasing or decreasing the applied voltage. The resulting material with the long name magic-angle twisted bilayer graphene (MATBG) has attracted the interest of the scientific community around the world.
In 2018, scientists changed the voltage applied to graphene using a single electrode. According to Daniel Rodan-Legrain, an MIT graduate student who participated in the study, they placed multiple electrodes in different areas of the material to generate different electric fields.
The team of scientists has found that it can “tune” different sections of graphene and change their degree of conductivity from zero to maximum. Then, using several electrodes, physicists were able to reproduce components of an electronic circuit from graphene, for which other materials are usually used.
Physicists turned their discovery into three working quantum electronic devices.
The first is a superconducting switch. It is a set of building blocks that make up quantum bits, and these in turn form the basis of quantum computers. They have other applications, for example, they are used as ultra-precise devices for measuring the characteristics of a magnetic field. The second is a tunneling spectroscope, which will help to better study superconductivity. And the third is a one-electron transistor, that is, a very sensitive device for controlling electric flows with an accuracy of one electron.
All three devices are good primarily because they are made of one material, easily adaptable to the needs of scientists. When something like this is done in a more traditional way, there are a lot of complications. Using different materials to create one device can lead to incompatibility of components. Rodan-Legrain notes that graphene makes the problem of incompatibility a thing of the past.
“MATBG makes it easy to reconfigure the device by applying different voltages to different areas of the material. There is no need to create different components and assemble the necessary device from them, ”says William Oliver, assistant professor of electrical engineering and computer science at MIT.
The work, published in the journal Nature Technology, opens up new opportunities for scientists. For example, graphene can be customized qubit, which can later be used in the development of quantum computers.
Also, experts hope that the properties of MATBG will help to better study the physics of superconductivity and in the future to develop a superconductor that can function at higher ambient temperatures than the current ones.
“We really hope that our discovery will become a kind of Rosetta stone and will help to better study the ‘relatives’ of superconductors that can tolerate higher temperatures,” says Rodan-Legrain.