Researchers from Nanjing University and Beihang University in China and the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg, Germany, have produced a new class of exciton with hybrid dimensionality by engineering the properties of layered silicon diphosphide (SiP₂). Their work has been published in Nature Materials.
Excitons are bound particles that consist of a negatively charged electron and a positively charged electron hole. Their exotic behavior offers an important new platform to study the physics of materials when they are coupled to other states of matter, such as vibrations of the material's crystal lattice.
Using SiP₂, researchers in China fabricated a new kind of material whose 2D layers are bound by van der Waals forces and feature strong internal covalent interactions. This produces peculiar one-dimensional phosphorus chains along which electronic states can localize. The team then managed to engineer a new kind of exciton with hybrid dimensionality in this layered material, meaning that the electron has a 1D character and the hole displays 2D characteristics. This is the first time such a phenomenon has been observed. Theoreticians at the MPSD confirmed the findings with advanced simulations.
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