Exploring the moiré effect of graphene structure through optical diffraction experiments

Abstract Moiré effect is a common phenomenon that arises from a slight mismatch in the period of two structures. A prominent example in the microscopic world is magic-angle twisted bilayer graphene (MATBG). In this work, to enhance undergraduate students' advanced learning of interference and diffraction, we reproduced the microscopic structure of MATBG on a macroscopic scale by creating hexagonal structured masks. By designing a suitable optical path, we were able to realize the optical diffraction of this macrostructure. The results revealed two additional periodic diffraction patterns in the twisted double-layer masks, which are relevant to the moiré effect. Through theoretical derivation and computer simulation, we explained the observed diffraction patterns, which matched well with the experiments. This designed project not only improves students' knowledge in optics and laboratory operation skills, but also deepens their comprehension of moiré effect and crystal diffraction, showcasing its potential for further expansion and application in undergraduate physics education.