induced by electron beam irradiation*

Shaping matter to provide a desired functionality has been a dream of the condensed matter, physics, and materials science communities. Recently, the field of twistronics has emerged as a route to achieving a tremendous variety of exotic electronic, optical, and quantum properties by creating periodically ordered structures in 2D materials. Until now, the only mechanism to induce this ordering has been a mechanical rotation between layers where the twist angle is related to both the moiré period and the resultant functional properties. A fundamentally new mechanism for the emergence of mesoscopic ordering - unrelated to twist - is uncovered in the metal phosphorous trichalcogenide, MnPS₃, and is induced by the electron beam. We demonstrate under the beam the formation of periodic hexagonal patterns with several characteristic length scales, explore the local dynamics and atomistic mechanisms, and consider the nanoplasmonics of the system. By exploiting these mechanisms with electron beam patterning, local control of functional and possibly exotic states may be realized. We suggest that this phenomenon not only provides insight into fundamental physics of quantum materials, but also allows for a new design pathway for device applications in developing moiré matter in 2D systems.