Xavier Roy

Columbia University

Abstract Title: Next level 2D quantum materials

Two-dimensional (2D) materials have received widespread attention in the past 15 years due to their remarkable physical, mechanical and chemical properties, and our ability to integrate them into devices. In this seminar, I will present our recent work in the development of the next generation of 2D materials. I will first discuss how magnetic order strongly couples to optical transitions in a new magnetic semiconductor developed in my laboratories, CrSBr. I will then introduce the synthesis and characterization of the first f-electron-based heavy fermion metal, CeSiI, that is also a 2D van der Waals (vdW) material. Conceptually, our synthetic design takes a traditional 3D intermetallic heavy fermion compound and slices it into atomically-thin vdW sheets by incorporating iodine into the structure. The resulting material is cleavable and effectively 2D electronically, even in bulk crystals. Finally, I will discuss the design of a two-dimensional (2D) flat band lattice model in air-stable monolayers of the van der Waals (vdW) intermetallic Pd₅AlI₂. In addition to being a material realization of the intriguing 2D decorated checkerboard model, this new structure demonstrates that flat bands can be designed in materials by considering both their lattice and orbital symmetries.

Short Bio:

Xavier Roy received a B.Eng. (2002) and a Master of Applied Science (2005) in Chemical Engineering from Ecole Polytechnique of Montreal, performing research under the guidance of Prof. Basil Favis. He earned his Ph.D. in Chemistry with Prof. Mark MacLachlan at the University of British Columbia in 2011, working as an NSERC Alexander Graham Bell Scholar. He went on to do postdoctoral research as a Canada NSERC Postdoctoral Fellow with Prof. Colin Nuckolls at Columbia University from 2011 to 2013. He joined the Columbia University Faculty in 2013 as an Assistant Professor of Chemistry, and was promoted in 2018 to the rank of Associate Professor and received tenure in 2020.