In the realm of physics, a team of researchers led by Zhigang Chen from the State University of New York at Buffalo, along with collaborators from the Institut National de la Recherche Scientifique (INRS) in Canada and the University of Zagreb in Croatia, has made a significant discovery about angular momentum conservation in discrete lattices. Their findings, published in the journal Nature Photonics, could have implications for the energy sector, particularly in the development of advanced materials for energy storage and conversion.
Angular momentum conservation is a fundamental law of physics that holds true in continuous systems. However, in discrete lattices, such as those found in certain crystalline materials, this conservation can deviate, especially when there are specific points where energy bands touch, known as band-touching points. The researchers focused on quadratic band-touching points (QBTPs) in two-dimensional lattices.
They found that, unlike in graphene lattices which have linear band-touching points (LBTPs), conventional angular momentum is not conserved near QBTPs. Instead, the team identified a generalized total angular momentum (GTAM) that remains conserved for both LBTPs and QBTPs. This GTAM is determined by the topological winding number at the band-touching point, a mathematical concept that describes how a field winds around a point in space.
To demonstrate this conservation principle, the researchers used a photonic Kagome lattice, a type of two-dimensional structure that can manipulate light in unique ways. They showed that GTAM conservation occurs through a process called pseudospin-orbital angular momentum conversion. This principle was found to extend to a broad class of discrete lattices with various pseudospin textures and higher-order winding numbers.
The practical applications of this research for the energy sector are still being explored. However, understanding and controlling angular momentum in discrete lattices could lead to the development of new materials with unique electronic and optical properties. These materials could be used in advanced energy storage systems, such as batteries and supercapacitors, or in energy conversion devices, like solar cells and thermoelectric materials. The ability to manipulate angular momentum at the atomic scale could also lead to more efficient and powerful energy technologies.
In summary, this research provides a unified framework for understanding angular momentum dynamics in discrete systems, bridging the gap between pseudospin, angular momentum, and topology. This fundamental understanding could pave the way for innovative energy technologies that harness the unique properties of discrete lattices.
This article is based on research available at arXiv.