The Variable Body Topological Insulator Of Graphene Under Certain Conditions

According to the Massachusetts Institute of Technology website recently, the school scientists found that in some extreme cases, graphene can be converted into a unique function of the topological insulator, is expected to provide new ideas for the manufacture of quantum computers. The research is published this week in the journal Nature.

The researchers found that the graphene flakes were placed in a low temperature environment with a strength of 35 Tesla magnetic field and 0.3 degrees Celsius higher than absolute zero. The conductive properties of graphene can be changed to allow it to filter electrons according to the direction of the electron spin, which is not currently available in any traditional electronic system.

Under typical conditions, graphene behaves as a normal conductor and exerts a voltage on it, and the current passes through it. But if a piece of graphene is placed in a magnetic field perpendicular to it, the properties of graphene change-the current only runs along the edges of graphene flakes, and the rest becomes insulators. In addition, the current will only move in one direction according to the direction of the magnetic field. This phenomenon is called the quantum Hall effect.

In the new study, the researchers found that if you add a strong magnetic field to the position of the graphene in the above case, the properties of graphene will change again: electrons still operate only along the edges of graphene, but the direction of the operation is changed from unidirectional to bidirectional, and the specific direction is determined by the different directions of the electron spin.

"We created an unusual special conductor," said a postdoctoral researcher at MIT's Physics department. It is a common function of the topological insulator to separate electrons according to the electron spin direction. However, graphene is not a topological insulator in the usual sense. We have the same effect in different material systems. More importantly, by changing the magnetic field, you can also at any time the direction of the electronic operation, power or not to control the state. This means that they can be made into circuits and transistors, which have not been achieved before. ”

Erero, an associate professor at MIT, said there had been predictions of this characterization of graphene, but no one had ever made it happen. The study first confirmed the selectivity of graphene to spin electrons, and it has been proved for the first time that graphene can control the direction of electronic operation and the state of electric power or not. The experiment has done what some researchers have been trying to achieve for decades without success, promising a new way to create quantum computers.

professor of physics at the Massachusetts Institute of Technology who participates in the study, says the study paints a new direction for the study of topological insulators. "We cannot predict what the findings will lead to, but it broadens our thinking and provides possibilities for the manufacture of multiple devices," he said. ”

said: "Because of the need for extreme low-temperature and strong magnetic environment, to achieve such a requirement is not easy, so the technology produced by the quantum computer will be a very professional equipment, may be used first for high-priority computing tasks." Next, they will test the performance of graphene at a lower magnetic field (1 Tesla) and at higher temperatures, with a view to reducing the threshold for the technology.