Seminar Date: Tuesday, May 13, 2025
Time: 11:00 AM PT
Location: 67-3111 & Zoom
Talk Title: Unveiling phonon-assisted phenomena using atom-wide electron beams
Zoom link
Add this event to your calendar

Abstract:
The development of atom-wide monochromatic electron beams in transmission electron microscopes has enabled the realization of phonon spectroscopy studies in nanomaterials with (sub)-nanometer spatial sensitivity. These spectroscopy capabilities are also permitting us to unveil physical processes assisted by phonons in the realms of infrared nanophotonic, nanoscale heat transfer, and quantum matter physics. In this seminar, we will describe progress along those directions by highlighting results involving: (i) Imaging and spectroscopy of hyperbolic phonon polaritons in twisted low-symmetry crystals. The focus is on the launching of hyperbolic phonon polaritons using fast electrons. (ii) Studies of heat transfer across nanoscale gaps. We seek to determine the spectral distribution of the thermal conductance between two objects subjected at different temperatures. (iii) Localized phonon behaviour across cuprate superconductor and semiconductor interfaces. These results represent progress towards understanding the role of phonons in physical process such as light-matter interaction and energy transfer.
Bio:
Maureen Joel Lagos is an Associate Professor at the Department of Materials Science and Engineering at McMaster University, Canada. His research is focused on the study of material properties using advanced imaging and electron spectroscopy techniques implemented in transmission electron microscopes. Specifically, he investigates elementary excitations (e.g.phonons, phonons) and electronic transitions in novel materials with potential for infrared nanophotonics, heat transport, and quantum material applications. His group also develops methodologies for nanoscale material characterization (e.g. thermometry). He holds the Canada Research Chair in Imaging and Spectroscopy of Advanced Nanomaterials.