Trilayer graphene shows signs of superconductivity

Science | AAAS | 7/17/2019 | Staff
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Last year, physicists reported that, when chilled to 1.7°C above absolute zero (–273°C), sheets of carbon atoms two layers thick can conduct electricity without resistance, allowing electrons to whiz through the material without losing any energy. The double sheets of carbons, known as bilayer graphene, have captivated researchers because their structural simplicity offered a platform to explore the complex physics of superconductivity, which is also exhibited in copper-oxide materials at much higher temperatures. Now, researchers have discovered signs of superconductivity in easy-to-make three-layer sheets of graphene, renewing hope that layered graphene will soon help researchers understand how superconductivity occurs in copper-oxides. That could lead to higher temperature superconductors—or even room temperature ones—which could produce massive energy savings in electrical grids and devices.

“It’s definitely an exciting development,” says Cory Dean, a physicist at Columbia University. Dean notes that bilayer graphene superconducts only when the atomic lattices of the two graphene layers are twisted with respect to one another by a “magic” angle of 1.1°—a difficult maneuver to perform on the thinnest material known. “If you’re off by a little bit it doesn’t work,” Dean says. The trilayer graphene, by contrast, doesn’t have to be twisted. Rather, the atomic lattice of each layer aligns with those above and below, which happens naturally when multilayer graphene is produced.

David - Goldhaber-Gordon - Physicist - Stanford - University

David Goldhaber-Gordon, a physicist at Stanford University in Palo Alto, California, and Feng Wang, a physicist at the University of California, Berkeley, and their colleagues followed a now-standard approach for isolating flakes of graphene. It starts by sticking a piece of Scotch tape on a bulk piece of graphite—the “lead” in most pencils—and peeling it off. Repeating the process leaves flakes of graphene sticking to the tape, some just a single sheet thick, but others with two and three layers. Wang’s team previously pioneered a technique...
(Excerpt) Read more at: Science | AAAS
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