Researchers have managed to find a way to trap interlayer excitons (IXs) and their quantum prints. The IXs are trapped by the engagement of two sheets of atoms composed of various transition metal dichalcogenides (TMDs), which are overlaid together with a small spin to create a moiré pattern.
The study was conducted by the Quantum Photonics Lab at Heriot-Watt, and a paper detailing it was published today, June 1st, in the top-tier journal Nature Materials.
For those unfamiliar with the quantum concept, moiré interference patterns appear whenever two alike but slightly counterbalanced templates are merged, such as silk fabric that has undergone heat pressure to give it a rippled shape. In the Quantum Photonics Lab, led by Professor Gerardot, the moiré patterns impact the main properties of atomic heterostructures to form a new quantum material.
Two-dimensional (2D) materials, including graphene or TMDs, can form different kinds of heterostructures held together by weak van der Waals (vdW) forces, providing researchers with a plentiful toolbox for engineering their optoelectronic properties. VdW multilayers can also form moiré patterns, which is a regular variation of the alignment between related atoms in adjacent layers, by distorting the sheets by a relative angle and/or mix materials with various lattice constants.
Creating New Quantum Materials
Moreover, odd characteristics appear from the 2-D nature of the TMD layers, such as a phenomenon known as spin-valley-layer locking, which unlocks potential connections to the broader field od spintronics and valleytronics that are significant for next-generation optoelectronic devices.
Professor Gerardot details the importance of his findings: “Interlayer excitons trapped in atomic moiré patterns hold great promise for the design of quantum materials based on van der Waals heterostructures, and investigations on their fundamental properties are crucial for future developments in the field.”
The scientific community still tries to find techniques to verify the nature of the trapping sites and understand the function of sample imperfections. A mix of experimental methods could be used to explain the role of atomic reconstruction, strain, and other flaws, associating optical measurements, and non-invasive microscopy techniques.
The Quantum Photonics Lab is creating fully-tuneable electronic devices, based on the warped quantum materials, to fully understand the way the moiré patterns can engage with each other and be used for quantum optics appliances.