In a recent study in Nature, scientists reported that moiré materials made from semiconductor materials can be superconducting, a property once considered to be exclusive to the graphene system.
Key points
- Exploring why semiconductor moiré materials behave differently from graphene in terms of superconductivity is key to advancing our understanding of quantum materials.
- This in turn can pave the way for new materials with more unusual properties — and unusual applications.
- The researchers explored superconductivity in twisted bilayer tungsten diselenide (tWSe₂), a moiré material created by stacking two layers of tungsten diselenide, a semiconductor, and rotating one layer by a small angle.
- Moiré materials are formed by the overlap of two or more two-dimensional (2D) lattices with small rotational or lattice constant differences, creating new periodic structures.
- Moiré materials have unusual electronic and quantum properties. The one made of graphene has even been found to be a superconductor.
- Even though the two layers of a moiré material have the same arrangement of atoms, the misalignment caused by the small twist produces a completely different pattern when seen from the top (see image above). This is called the moiré pattern.
- In moiré materials, the moiré pattern gives rise to new behaviours that are not present in the individual 2D materials alone. This is because the twist leads to the formation of flat bands in the electronic structure of the material.
