Surprise graphene discovery could unlock secrets of superconductivity - Sensationalist Headlines

https://www.nature.com/articles/d41586-018-02773-w Take two sheets of graphene, bring them together, then rotate one of them slightly and you end up with a system that exhibits superconductivity below 1.7K. On it's own, this isn't terribly useful, but the system shows properties of being an unconventional superconductor. Conventional superconductors are those which can be explained by BCS theory, while unconventional superconductors are those that cannot. Despite having been discovered 30 years ago, a theory of unconventional superconductivity still eludes us. If confirmed to be an unconventional superconductor, the magic-angle graphene system will allow us to study unconventional superconductivity with greater ease, and hopefully give us some insights into this phenomenon. The two articles referred to are linked here for convenience: Unconventional superconductivity in magic-angle graphene superlattices Correlated insulator behaviour at half-filling in magic-angle graphene superlattices

The magic angle in this case comes about due to the specific Moiré pattern generated by rotating one sheet of graphene with respect to the other. Depending on the angle, the pattern generated will change, as will the properties of the system. When the two sheets are rotated at the "magic angle", the resulting pattern (and system) just so happens to exhibit the properties described. The illustration in the article gives a nice example of this: https://media.nature.com/w800/magazine-assets/d41586-018-02773-w/d41586-018-02773-w_15507796.jpg

So the Moiré pattern generated by rotating two layers of graphene at an angle of 1.1º results in a large hexagonal lattice.. the same way that the graphene itself is a hexagonal lattice at the atomic scale? Yo. That's some geometric-secrets-to-the-universe shit. I hope we learn more from this and it isn't immediately disproven to be malarkey.

Maybe all that generic Sci fi visual design where everything is made out of hexagons actually does have a point.

If it's true, bees have had the upper hand for millions of years now. We need to step our game up.

If they do die out at least we will have a hexagonal future to remember them by. Or the hexagon will lead to our own demise and the bees are cautionary tale of dabbling in the art of geometry.

I wonder if it's just finding the path of lease resistance as that image has larger holes than if they were both layed upon top of each other.

Each layer of graphene has a cloud of electrons above and below each sheet, which is what allows graphene to conduct electricity. When two sheets are stacked together, the clouds between the layers overlap each other. Keep stacking layers on top of each other and you eventually end up with graphite. This page gives a decent, reasonably accessible explanation of this. In this present study, the twisting of the layers creates a misalignment: in some areas the carbon atoms line up perfectly on top of each other, while in others the carbon atoms are on top of the hexagonal rings. This causes the electron clouds to overlap in funny ways, which leads to the observed behaviour. Why this happens will be the topic of further studies.