Wang finds unique properties by giving three layers of graphene a twist

Ke Wang, an Assistant Professor in the School of Physics and Astronomy, led a recent experimental effort to study the electrical properties of a novel architecture of graphene--a single atomic layer of graphite. It was recently shown that by placing two layers of graphene on top of one another with a small twist angle in between, the electrical properties change drastically. “With a precisely-controlled twist angle,” Wang says, “it can even become superconducting, allowing electrical current to experience no dissipation or resistance.” Wang’s group took it to another level by stacking three layers of graphene with consecutive twists, resulting in a higher order atomic structure that exhibits “transport signature of superconductivity at an extremely low electron density, two orders of magnitude smaller than the previous record,” Wang says. The experimental results have also shed important new light on understanding superconductivity in graphene. “It was believed that electrons need to be energetically isolated before they can give rise to superconductivity in graphene, but our experiment surprisingly suggests otherwise.” 

While still at the fundamental physics stage, this discovery promises an atomically-clean superconductor that can be precisely and sensitively tuned with electrical control. “This could lead to a game-changing component for the next generation of quantum electronic devices, including rewritable on-chip quantum interferometers and quantum computing platforms”.  Towards that goal, the next move for Wang’s group is to study the structural properties of twisted-trilayer graphene with various experimental techniques, and to fabricate gate-defined nanostructures to manipulate the electron flow to reveal novel quantum phenomena and harnessing them for future quantum device application.