Phys.org November 11, 2024 Photonic modes exhibiting polarization winding akin to a vortex possess an integer topological charge. Lasing with topological charge 1 or 2 can be realized in periodic lattices of up to six-fold rotational symmetry—higher order charges require symmetries not compatible with any two-dimensional Bravais lattice. Researchers in Finland experimentally demonstrated lasing with topological charges as high as −5, +7, −17 and +19 in quasicrystals. They discovered rich ordered structures of increasing topological charges in reciprocal space. Their quasicrystal design utilized group theory in determining electromagnetic field nodes, where lossy plasmonic nanoparticles were positioned to maximize gain. According […]
Tag Archives: Quasicrystals
Physicists coax superconductivity and more from quasicrystals
Phys.org September 28, 2023 Owing to their complexity and scarcity, quasicrystals are underexplored relative to periodic and amorphous structures. An international team of researchers (USA – MIT, Japan, Israel) introduced a new type of highly tunable quasicrystal easily assembled from periodic components. By twisting three layers of graphene with two different twist angles, they formed two mutually incommensurate moiré patterns. In contrast to many common atomic-scale quasicrystals, the quasiperiodicity in their system was defined on moiré length scales of several nanometres. This ‘moiré quasicrystal’ allowed them to tune the chemical potential and thus the electronic system between a periodic-like regime […]