Physicists at the National University of Singapore (NUS) have made significant progress in aligning supermoiré lattices, which could revolutionize the potential for next-generation moiré quantum matter. The researchers at NUS have developed a technique to precisely control the alignment of supermoiré lattices, using a set of golden rules. This breakthrough paves the way for advancements in moiré quantum matter.
Moiré patterns are created when two identical periodic structures are overlaid with a relative twist angle, or two different periodic structures are overlaid with or without a twist angle. In the case of graphene and hexagonal boron nitride (hBN), the atoms in the two structures do not line up perfectly, resulting in a pattern of interference fringes called a moiré pattern. This leads to an electronic reconstruction with exotic properties.
The combination of multiple moiré patterns stacked together creates a supermoiré lattice, which offers expanded tunable material properties. This opens up possibilities for a wider range of applications compared to traditional single moiré materials.
The NUS research team, led by Professor Ariando from the NUS Department of Physics, has successfully developed a technique to control the alignment of the hBN/graphene/hBN supermoiré lattice. They have also formulated the “Golden Rule of Three” to guide the use of their technique. These achievements were recently published in the journal Nature Communications.
Creating a graphene supermoiré lattice poses several challenges. Traditional optical alignment techniques rely heavily on the straight edges of graphene, which can be time-consuming and labor-intensive. Additionally, the uncertainty of edge chirality and lattice symmetry makes it difficult to obtain a double-aligned supermoiré lattice. Often, alignment errors are large due to the challenges of aligning different lattice materials.
Dr. Junxiong Hu, the lead author of the research paper, explained that their technique solves these problems by reducing fabrication time and improving sample accuracy. The technique involves a “30° rotation technique” to control the alignment of the top hBN and graphene layers, as well as a “flip-over technique” to control the alignment of the top hBN and bottom hBN layers. These methods allow for precise lattice symmetry control and band structure tuning, leading to the fabrication of highly accurate moiré samples.
Professor Ariando emphasized the significance of their work and its potential impact on the field of two-dimensional materials. He expressed hope that the technique will accelerate the development of the next generation of moiré quantum matter. The research team is currently utilizing the technique to fabricate single-layer graphene supermoiré lattices and explore their unique properties. They are also extending the technique to other material systems to discover additional quantum phenomena.
This breakthrough in aligning supermoiré lattices opens up new possibilities for the development of next-generation moiré quantum matter. With precise control over these lattices, researchers can explore a wider range of material properties and applications. The advancements made by the NUS physicists have the potential to revolutionize the field and accelerate the discovery of new quantum phenomena.