Researchers succeed in coupling two types of electron-hole pairs

Several research groups have been working on two-dimensional van der Waals materials. These structures are created in the laboratory by combining atom-thick layers of different materials in a process called "atomic Lego". Heterostructures can show properties that the individual constituents don't.

One such van der Waals material is two layers of Molybdenum disulfide. The negatively charged particles leave their place in the band and enter the band through a hole. A quasiparticle is formed when electrons and holes are attracted to each other. The latter can move freely within the material.

There are two different types of electron-hole pairs, in which the hole is in the same layer of the material, and interlayer pairs, in which the hole is in a different layer.

In other words, the two types of electron-hole pairs are very bright. Interlayer excitons can be shifted to different energies, allowing researchers to adjust the absorbed wavelength. Interlayer excitons have an essential role to play in many of their potential applications.

The properties are coming together.

The two types of electron-hole pairs were brought to the same energies by the researchers from the Department of Physics and the University of Basel. Thanks to the adjustability of interlayer excitons, this convergence is possible. The researchers can make merged particles that are bright and strong.

Lukas Sponfeldner is the first author of the paper and is a PhD student at the school. A novel source of individual photons, which are a key element of quantum communication, could be produced by merging these properties.

Classical models are compatible.

Classical models from the fields of mechanics or electronics can be used to model the system of electron-hole pairs.

An electron-hole pair can be described as a circuit. "These simple and general analogies help us to understand the fundamental properties of coupled particles, not only in Molybdenum disulfide but also in many other material systems and contexts."

More information: Lukas Sponfeldner et al, Capacitively and Inductively Coupled Excitons in Bilayer MoS₂, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.129.107401 Journal information: Physical Review Letters