MSE Talk with Matthieu Fortin-Deschenes

Speaker: Matthieu Fortin-Deschenes Title: Direct Growth of Tunable Moiré Heterostructures

Abstract: A twist angle or lattice mismatch between two atomic layers induces a larger quasi-periodic lattice called a moiré pattern. Moiré materials display highly tunable quantum properties such as correlated states and moiré trapped excitons. However, growing moirés with a precisely controlled periodicity is very challenging since twisted configurations are metastable, and the moiré period in rotationally aligned heterostructures is determined by the equilibrium lattice mismatch. This talk will discuss a new thermodynamically driven approach to grow tunable moirés based on lattice-mismatch engineering. By controlling the substitutional alloying of chalcogens in individual layers of transition metal dichalcogenides van der Waals (vdW) heterostructures, we tune the moiré period from 10-45 nm. Furthermore, using transmission electron microscopy and modelling of moiré nuclei, we elucidate the interplay between interlayer interactions, bulk strain, and edge stress in shaping the moiré growth mechanisms. These results lay the groundwork for the large-scale growth of tunable moiré materials.

Speaker Bio: Matthieu Fortin-Deschenes is a postdoctoral fellow in Electrical Engineering at Yale University. He obtained his Ph.D. in Engineering Physics from Polytechnique Montreal in 2020. His research focuses on establishing new avenues to implement nanomaterials using atomic-level engineering processes, while addressing crucial questions about their formation mechanisms and scalability potential.

Student Host: Jing Tang