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Colloquium | Nanoscience and Technology

Multifunctional van der Waals Quantum Materials

Abstract: 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.  

Bio: Xavier Roy received a B.Eng. and a Master of Applied Science in Chemical Engineering from Ecole Polytechnique of Montreal. He earned his Ph.D. in Chemistry at the University of British Columbia. 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.