Materials Science Research Lecture

***Refreshments at 3:45pm in Noyes lobby

Abstract:
Anharmonic vibrational dynamics play a crucial role in determining the physical properties of crystalline materials, impacting thermal conductivity, phase transitions, ion transport, and optoelectronic behavior.

In this talk, I will present an intuitive framework for understanding anharmonicity and demonstrate how Raman spectroscopy, combined with coupled mode models, provides a powerful tool for probing these dynamics. I will illustrate this approach through three case studies: (1) the temperature evolution of hydrogen-bond vibrations in glycine crystals, (2) soft modes and phase transitions in bismuth vanadate, and (3) electron-phonon coupling in heavily doped silicon.

A key takeaway from this analysis is that modeling with coupled mode pairs, rather than a single damped oscillator, effectively captures material behavior, bridging equilibrium and non-equilibrium dynamics and providing deeper insight into complex vibrational interactions in crystals.

More about the Speaker:

Omer Yaffe is an Associate Professor at the Weizmann Institute of Science, where he leads a research group focused on anharmonic lattice dynamics. His work combines experimental techniques, particularly advanced Raman spectroscopy, with theoretical modeling to explore how lattice vibrations influence charge transport, phase transitions, and ion conduction.