The "magic angle" for making graphene a superconductor may be less stringent than previously thought

Researchers at The Ohio State University, in collaboration with University of Texas, Dallas scientists and the National Institute for Materials Science in Japan, have found that graphene is more likely to become a superconductor than originally thought possible.

Finding the “magic angle” to create a new superconductor image(A) Schematic diagram of device geometry. (B) Schematic diagram of moiré superlattice formed by the twisted graphene layers. Image from Science Advances

“Graphene by itself can conduct energy, as a normal metal is conductive, but it is only recently that we learned it can also be a superconductor, by making a so-called ‘magic angle’ – twisting a second layer of graphene on top of the first,” said Jeanie Lau, a professor of physics at Ohio State and co-author of the paper. “And that opens possibilities for additional research to see if we can make this material work in the real world.”

Researchers reach graphene-based junctions that are both electrically and mechanically stable

A research team jointly led by University of Warwick and EMPA has tackled a challenging issue of stability and reproducibility in working with graphene, that meant that graphene-based junctions were either mechanically stable or electrically stable but not both at the same time.

Researchers tackle a known limitation of graphene junctions imageCredit: University of Warwick

Graphene and graphene like molecules are attractive choices for electronic components in molecular devices, but have proven very challenging to use in large scale production of molecular devices that will work and be robust at room temperatures. The joint research team from the University of Warwick, EMPA and Lancaster and Bern Universities has reached both electrical and mechanical stability in graphene-based junctions.

Graphene discovery could help develop room temperature superconductors

A research team led by Rutgers University has discovered that in the presence of a moiré pattern in graphene, electrons organize themselves into stripes, like soldiers in formation. The team's findings could help in the search for quantum materials, such as superconductors, that would work at room temperature. Such materials would dramatically reduce energy consumption by making power transmission and electronic devices more efficient.

Electrons organize in lines in magic layer graphene imageLeft: image shows a moiré pattern in "magic angle" twisted bilayer graphene. Right: Scanning tunneling charge spectroscopy, shows correlated electrons. Credit: Rutgers University

"Our findings provide an essential clue to the mystery connecting a form of graphene, called twisted bilayer graphene, to superconductors that could work at room temperature," said senior author Eva Y. Andrei, Board of Governors professor in the Department of Physics and Astronomy in the School of Arts and Sciences at Rutgers University–New Brunswick.

Stanford team finds novel form of magnetism in twisted bi-layer graphene

Stanford physicists recently observed a novel form of magnetism, predicted but never seen before, that is generated when two graphene sheets are carefully stacked and rotated to a special angle. The researchers suggest the magnetism, called orbital ferromagnetism, could prove useful for certain applications, such as quantum computing.

bi-layer graphene between hBN gives off orbital ferromagnetism imageOptical micrograph of the assembled stacked structure, which consists of two graphene sheets sandwiched between two protective layers made of hexagonal boron nitride. (Image: Aaron Sharpe)

“We were not aiming for magnetism. We found what may be the most exciting thing in my career to date through partially targeted and partially accidental exploration,” said study leader David Goldhaber-Gordon, a professor of physics at Stanford’s School of Humanities and Sciences. “Our discovery shows that the most interesting things turn out to be surprises sometimes.”

Unique device that combines graphene and boron nitride can switch from superconducting to insulating

Researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have designed a graphene device that switches from a superconducting material to an insulator and back again to a superconductor — all with a flip of a switch. The team shared that the device exhibits this unique versatility while being thinner than a human hair.

Graphene and hBN device moves from insulating to superconducting imageViews of the trilayer graphene/boron nitride heterostructure device as seen through an optical microscope. The gold, nanofabricated electric contacts are shown in yellow; the silicon dioxide/silicon substrate is shown in brown and the boron nitride flakes

"Usually, when someone wants to study how electrons interact with each other in a superconducting quantum phase versus an insulating phase, they would need to look at different materials. With our system, you can study both the superconductivity phase and the insulating phase in one place," said Guorui Chen, the study's lead author and a postdoctoral researcher in the lab of Feng Wang, who led the study. Wang, a faculty scientist in Berkeley Lab's Materials Sciences Division, is also a UC Berkeley physics professor.

Versarien - Think you know graphene? Think again! Versarien - Think you know graphene? Think again!