When two sheets of graphene are stacked atop each other at just the right angle, the layered structure morphs into an unconventional superconductor, allowing electric currents to pass through without resistance or wasted energy.

This “magic-angle” transformation in bilayer graphene was observed for the first time in 2018 in the group of Pablo Jarillo-Herrero, the Cecil and Ida Green Professor of Physics at MIT. Since then, scientists have searched for other materials that can be similarly twisted into superconductivity, in the emerging field of “twistronics.” For the most part, no other twisted material has exhibited superconductivity other than the original twisted bilayer graphene, until now.

In a paper appearing today in Nature, Jarillo-Herrero and his group report observing superconductivity in a sandwich of three graphene sheets, the middle layer of which is twisted at a new angle with respect to the outer layers. This new trilayer configuration exhibits superconductivity that is more robust than its bilayer counterpart.

The researchers can also tune the structure’s superconductivity by applying and varying the strength of an external electric field. By tuning the trilayer structure, the researchers were able to produce ultra-strongly coupled superconductivity, an exotic type of electrical behavior that has rarely been seen in any other material.

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