Zoe Berg, Senior Photographer

Yale researchers have found a new way to create materials with unique electronic, magnetic and optical properties. 

Moiré material is a type of material that exhibits different properties than its original material. Though researchers recently discovered the materials in 2018, they have quickly become a topic of interest, spawning a new branch of research known as “twistronics.” 

“Visually, the material looks very different from the traditional material, its parental form,” said Fengnian Xia, a professor of electrical engineering and an author of the study. “Because of the composition, how it is organized is very different from traditional materials. As a result, moiré materials have very different properties from the parent materials.”

Moiré materials are defined both by how they are formed and the properties they exhibit. Initially, moiré materials were constructed by stacking anatomically thin sheets at small relative angles.  

Xia and his team found a new way to grow these materials by stacking misaligned layers of van der Waals materials to create lattice structures. By placing successive sheets on top of one another at different angles, the researchers established a more thermodynamically stable configuration. Previously, the materials tended to rotate back to their “ground state,” which is the rotationally aligned configuration.

To visualize this process, Xia said to imagine that the materials are like hands stacked on top of one another at different angles. The various angles that result between the hands act in the same way that moiré materials are formed.

For Matthew Fortin-Deschênes, a postdoctoral fellow in Xia’s lab and the primary author of the paper, moiré materials’ unknown properties are exciting. He said that they could currently be used in many applications, including optics and electrical engineering. 

Benjamin Remez, a postdoctoral fellow in the Physics Department, studies theoretical condensed matter physics. His research focuses on the novel physics that occurs when many particles are brought together. Even though Xia’s study is not directly related to his work, he believes it has powerful implications. 

“It is important to know what is within reach for experimentalists to probe,” Remez said. As the field of materials science advances in synthesizing new materials with new methods that allow scientists to have more tunability and control over the growth, the collaboration between theory and experiment becomes more prominent.

Similarly, Nemin Wei, a postdoctoral fellow who studies condensed matter theory, said that Xia and his team’s findings are a critical first step in controlling the electronic and optical properties of the material. 

Although the study’s primary goal was to find a new way to create moiré materials, Xia and Fortin-Deschênes both plan to continue their research. They have successfully grown moiré materials to roughly 50 microns. Still, the researchers would like to grow these materials consistently at a higher scale. Further, they would like to apply their new method of material growth on different base materials. 

Electronics, photonics and nanodevices is a research concentration in the Electrical Engineering Department.