Post by Baron von Lotsov on Mar 22, 2023 12:58:37 GMT
A moiré pattern is probably something you have seen already without realising it. Say you take two regular patterns and lay one on top of another and then turn one relative to the other, then you will see larger scale regular patterns emerge. This wiki link shows you some pictures of examples.
Now all this trick is doing is using two regular sheets of atoms and layering them on top of one another but at a critical angle in order to get large scale patterns in the atomic lattice. Graphene is for example a two dimensional hexagonal grid of carbon atoms, so if you take two sheets of graphene and I think the angle is 1.3 degrees for this, you will get your desired larger scale patterns in these atoms.
So what you may ask. Well it is a big so what, because if we analyse it using quantum mechanics we end up with a system constrained by quantum rules, such as the Pauli exclusion principle which applies to atoms. No single electron can occupy identical quantum states, and like if you take the first orbit of an atom, you can have two electrons, where if one is spin up the other must be spin down, because electrons are classed as fermions. What we find is these quantum rules apply equally to these virtual atoms made out of moiré patterns. These atoms can be very large, like much larger than regular atoms. Not only this but electrons can tunnel so they can hop from one virtual atom to another like they do in a metal. They can also function as a semiconductor with valency bands, just as in all the physics we get for normal semiconductors applies here as well although what you get has different characteristics, much as if you looked at silicon and germanium as a semiconductor.
If you would like a scientific reference to this work I have a presentation of it from the guy who came up with it. He's not the best speaker in the world and so i would advise using subtitles.
His name is Kin Fai Mak and he researches at Cornell University