Conductors - Page 4

Haydale has launched a range of graphene-enhanced prepreg materials for lightning-strike protection, utilizing functionalized graphene to improve the electrical conductivity.

The material has been developed in collaboration with Airbus UK, BAE Systems, GE Aviation and Element Materials Technology Warwick, within the NATEP-supported GraCELs project where the first iterations of materials were developed and subjected to lighting strike tests. The consortium is now looking to manufacture a demonstrator component using the materials developed to establish composite manufacturing protocols as a showcase part for commercial purposes.

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.

(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.

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.

Credit: 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.

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.

Left: 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 UniversityNew Brunswick.

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.

Optical 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.

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.

Views 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.

A team of researchers led by Columbia University have developed a new method to finely tune adjacent layers of graphene, in a research that provides new insights into the physics underlying the material's intriguing characteristics.

"Our work demonstrates new ways to induce superconductivity in twisted bilayer graphene, in particular, achieved by applying pressure," said Cory Dean, assistant professor of physics at Columbia and the study's principal investigator. "It also provides critical first confirmation of last year's MIT results - that bilayer graphene can exhibit electronic properties when twisted at an angle - and furthers our understanding of the system, which is extremely important for this new field of research".

A study by Brazilian physicist Aline Ramires with Jose Lado, a Spanish-born researcher at the Swiss Federal Institute of Technology (ETH Zurich), showed that a simple sheet of graphene has fascinating properties due to a quantum phenomenon in its electron structure called Dirac cones. The system becomes even more interesting if it comprises two superimposed graphene sheets, and one is very slightly turned in its own plane so that the holes in the two carbon lattices no longer completely coincide. For specific angles of twist, the bilayer graphene system displays exotic properties such as superconductivity.

The researchers found that the application of an electrical field to such a system produces an effect identical to that of an extremely intense magnetic field applied to two aligned graphene sheets. "I performed the analysis, and it was computationally verified by Lado," Ramires said. "It enables graphene's electronic properties to be controlled by means of electrical fields, generating artificial but effective magnetic fields with far greater magnitudes than those of the real magnetic fields that can be applied."

Researchers at MIT and Harvard University have found that graphene can be tuned to behave at two electrical extremes: as an insulator, in which electrons are completely blocked from flowing; and as a superconductor, in which electrical current can stream through without resistance.

Researchers in the past, including this team, have been able to synthesize graphene superconductors by placing the material in contact with other superconducting metals — an arrangement that allows graphene to inherit some superconducting behaviors. In this new work, the team found a way to make graphene superconduct on its own, demonstrating that superconductivity can be an intrinsic quality in the purely carbon-based material.

Researchers at the University of Cambridge, managed to activate graphene's potential to superconduct by coupling it with a material called praseodymium cerium copper oxide (PCCO). The researchers suggest that superconductive graphene could have interesting applications; It could be used to create new types of superconducting quantum devices for high-speed computing, and it might also be used to prove the existence of a form of superconductivity known as "p-wave" superconductivity, which academics have been struggling to verify for many years.

Graphene's ability to superconduct has been speculated but thus far has only been achieved by doping it with, or by placing it on, a superconducting material - a process that can compromise some of its other properties. "Placing graphene on a metal can dramatically alter the properties so it is technically no longer behaving as we would expect," the team stated. "What you see is not graphene's intrinsic superconductivity, but simply that of the underlying superconductor being passed on."