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'Magic' Angle Graphene Is BACK with an Even Bigger Twist

graphene and superconductors

last year. The physics world was sent into a tizzy by the discovery of a ‘magic angle’ in graphene.
Angle Graphene Is BACK with an Even Bigger Twist
'Magic' Angle Graphene Is BACK with an Even Bigger Twist 

Now, graphene is a single-atom-thick layer of carbon that forms a hexagonal lattice pattern, and its atomic arrangement gives it certain exciting properties, like being over 200 times stronger than steel, flexible, transparent, and highly conductive. This last property was highlighted in 2018 when researchers put two layers of graphene on top of each other and twisted them at exactly 1.1 degrees.

They cooled the graphene structure to just above absolute zero, applied a strong electric field, and found that not only are these graphene bilayers highly conductive, but they also exhibit alternating areas of conductivity and insulation. So in some areas, they saw graphene bilayers with a twist to behave like a superconductor. That means there’s no resistance to an electrical current and therefore, the current can flow super efficiently.

magic-angle twisted bilayer graphene devices

But here’s the kicker: we don’t know why! We don’t fully understand what’s happening at the molecular level to make this particular orientation of graphene capable of superconduction And this year, in further exploring the capabilities of this seemingly ‘magical’ twist, scientists have now discovered something that is arguably an even bigger deal. An international team at the Institute of Photonic Science in Barcelona ‘cleaned up’ the experiment.

They made what they call ‘magic-angle twisted bilayer graphene devices’, a name that will never get old for me. Essentially, they took these two stacks of graphene rotated at the magic angle and used a mechanical squeezing process to eliminate impurities. This squeaky clean version of the experiment allowed them to see details they hadn’t before like the device’s incredible versatility.

It turns out, graphene stacked and turned at the magic angle can be tuned to act as many things. Depending on the charge running through it, the experimental setup could act as an insulator, a superconductor, or even a magnet! And just by changing the current running through the device, scientists could turn states on and off, which is exciting for many reasons.

Areas of use graphene materials

It could make these materials really useful inside electronics, as they're controllable in much the same way our current electronics are: they’re tunable. But this new research is also a step toward solving the mystery of exactly how this happens. Work like this lets us explore and manipulate the microscopic world inside graphene devices, allowing us to better understand how this material works and how we can use it.

In addition to furthering our existing understanding of how these bilayer graphene stacks behave, the team was able to beat the record temperature at which the material behaves as a superconductor. And this is incredibly important, as our existing ways of inducing superconducting behavior in most materials require extremely low temperatures and/or high pressures.

Superconductors would be so useful if they didn’t require such low temperatures to function. And in the field of physics, discovering or creating a room-temperature superconductor is considered something of a holy grail. This most recent graphene work has demonstrated that graphene magic angle bilayer devices can act as superconductors at a temperature above 3 Kelvin—which, while not the warmest, is the highest temperature ever demonstrated for a graphene superconductor. Along with graphene’s other tantalizing properties, achieving superconductivity at easier-to-maintain temperatures could be seriously useful in many future applications.

Things like incredibly efficient power transfer, hovertrains, or even quantum computing. But that future can only really become a reality if we develop a better understanding of the mechanisms of action at play, and can use that understanding to improve the performance of ‘magic’ materials like this.

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