At the confluence of twisted magic angle nanosandwiches and the much bigger news of the accidental Kuhning of the universe comes an unlikely character, the moiré lattice.
It's a grid, the two-dimensional piece of molecular paper epitomized as the graphene sheet, but it's two of them sandwiched on top of each other, and then turning one slightly so the grid no longer matches up. It's like the chain link fence that creates undulating optical illusions when layered with another fence; these two nanosheets do weird things to the field that exist between them.
Moiré lattices are being used to create weird crystals, so they're a big part of optoelectronics because crystals manipulate lasers. And they're also providing a novel model of physical interaction that's unexpectedly mirrored in the fabric of spacetime, which might give us a very different idea about how the universe works.
Image credit: Fence-art by Todd Kreher ink on paper 2015
New quasiparticle discovered in moiré patterns
Nov 2022, phys.org
They found an exciton in there - an electrically neutral quasiparticle that can carry energy and consists of an electron and electron "hole" that can be created for example by light impinging certain semiconductors and other materials.
Coming soon - "post-silicon nanoscale optoelectronic devices"
via University of Texas at Austin: Mit H. Naik et al, Intralayer charge-transfer moiré excitons in van der Waals superlattices, Nature (2022). DOI: 10.1038/s41586-022-04991-9
Moiré superlattices show superpower in photonics and optoelectronics
Mar 2023, phys.org
"The era of moiré photonics and optoelectronics is coming."Moiré superlattices are artificial quantum materials formed by vertically stacking two or more two-dimensional (2D) layered materials with a slight lattice mismatch and/or a small rotational twist. They introduce a potential landscape of much larger length scale than the crystal periodicity of the constituent 2D layers, providing a novel paradigm for engineering band structures and hence a plethora of exotic quantum phenomena.
via Chinese Academy of Sciences: Luojun Du et al, Moiré photonics and optoelectronics, Science (2023). DOI: 10.1126/science.adg0014.
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Post Script:
New one for me - "Ab initio" calculations ("from the beginning) are computations of electronic orbitals with no other hypotheses than Coulomb interactions between all electrons and nuclei with electrons obeying Fermi statistics with the Pauli exclusion principle.
Or - the only inputs into an ab initio calculation are physical constants; Ab initio quantum chemistry methods attempt to solve the electronic Schrödinger equation given the positions of the nuclei and the number of electrons [wiki]
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