Researchers map tiny twists in “magic-angle” graphene

news
11/05/2020

Results could help designers engineer high-temperature superconductors and quantum computing devices.

Made of a single layer of carbon atoms linked in a hexagonal honeycomb pattern, graphene’s structure is simple and seemingly delicate. Since its discovery in 2004, scientists have found that graphene is in fact exceptionally strong. And although graphene is not a metal, it conducts electricity at ultrahigh speeds, better than most metals.

In 2018, MIT scientists led by Pablo Jarillo-Herrero and Yuan Cao discovered that when two sheets of graphene are stacked together at a slightly offset “magic” angle, the new “twisted” graphene structure can become either an insulator, completely blocking electricity from flowing through the material, or paradoxically, a superconductor, able to let electrons fly through without resistance. It was a monumental discovery that helped launch a new field known as “twistronics,” the study of electronic behavior in twisted graphene and other materials.

Now the MIT team reports their latest advancements in graphene twistronics, in two papers published this week in the journal Nature.

In the first study, the researchers, along with collaborators at the Weizmann Institute of Science, have imaged and mapped an entire twisted graphene structure for the first time, at a resolution fine enough that they are able to see very slight variations in local twist angle across the entire structure.

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