October 6, 2022
Dr. Xavier Roy
Host: Dr. Dan Rhodes (MS&E)
Multifunctional van der Waals Quantum Materials
Semiconductors, featuring tunable electrical transport and delocalized excitons, and magnets, featuring tunable spin configurations, form the basis of nearly all information technologies. A long-standing challenge has been to realize materials that integrate these two distinct properties. Two-dimensional (2D) materials offer a new platform to realize this concept, but the recently discovered 2D magnetic semiconductors are found to be electrically insulating in their magnetic phase. In this talk, I will discuss the magnetic control of electron transport and optical transitions within the magnetic phase of the 2D semiconductor CrSBr, which reveals strong coupling between magnetic order and electronic structure. This provides a previously unrealized opportunity to characterize the layer-dependent magnetic order and coherent magnons of CrSBr via magnetotransport and optical spectroscopy. I will then discuss how the magnetic properties of CrSBr can be modified with strain, and composition. Finally, I will introduce two new classes of 2D metals, highlighting their unique physical properties, including magnetic order, heavy fermion state, and charge density wave.
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.