Nanoscale Molecular and Ionic Diffusion in Quantum Materials

with Dr. Yohannes Abate
Professor, University of Georgia

ABSTRACT: Interaction with diffusion-driven ions or molecules could enable to reconfigure quantum materials, leading to a range of intriguing phenomena, including surface, subsurface, and interface modifications, as well as changes in electronic, optical, and chemical properties. However, understanding the action of molecular and ionic diffusion at the nanoscale presents a formidable challenge in unraveling the fundamental mechanisms involved. In this talk, I will present recent results that provide quantitative insights into the role of diffusion-driven ionic or molecular interactions in altering the complex dielectric function of two classes of quantum materials: correlated oxides and van der Waals (vdW) crystals at the nanoscale. Our recent works reveal how an applied field perturbs ion diffusion at the nanoscale in correlated oxides, leading to ordered reconfigurable phases. This reconfigurability enables the design of robust artificial synapses and opens new frontiers for fundamental understanding of memory, learning, and information retention for brain-inspired information processing. The interaction of vdW crystals with diffusing oxygen and water molecules in an ambient environment leads to enhanced chemical reactivity of their extraordinarily high surface areas. Using nano-optical correlative imaging and spectroscopy, I will present recent results revealing exotic interfacial vdW interactions, exciton diffusion and the formation of oxidized molecular species in 2D transition metal dichalcogenides heterostructures and thin flakes of phosphorus allotropes. I will also present a recent exciting work on the connection between diffusion and topology, focusing on the role of path-connectivity as a topological invariant elucidating a fundamental link between path connectedness and probabilistic phenomena in materials physics.

BIOGRAPHY: Professor Abate joined the University of Georgia (UGA) as an associate professor of physics in August 2017. He received his PhD in Physics at the University of Iowa in 2006. From 2006-2009 he was a postdoctoral research fellow at the University of California, Berkeley and Lawrence Berkeley National Laboratory. In September of 2009 he has spent time as a Visiting Scientist at the Nano-Photonics Laboratory, Max-Planck-Institut für Biochemie, Martinsried, Germany. He has received the NSF Career Award (2016) and in 2023 he has been selected by the Gordon and Betty Moore Foundation as one of its 2023 Experimental Physics Investigators. He received the BS degree in physics from Addis Ababa University, Ethiopia, and MS degree in physics from the National Institute of Physics, University of the Philippines, Diliman. He is a member of the American Physical Society and Materials Research Society.

With refreshments from Panera Bread