Abstract: Quantized vibrations in condensed phases, phonons, obey the laws of quantum mechanics in the same way as electrons and photons, which are commonly exploited as energy and/or information carriers. Efforts to control phonons, especially at micro- and nanoscale, have been stimulated by the ever-increasing roles that phonons assume via self-interaction and interacting with electrons and photons. Phonon engineering has seen rapid progress through understanding of structure-processing-property relationships that connect nanoscale structures, dictated by methods of fabrication and processing, and vibrational and thermal transport properties. However, a broad range of phonon frequencies needs to be engineered, in contrast with electronic applications, where only energies close to the Fermi level are relevant. The difficulty of working with a broad spectrum of excitations naturally poses major challenges in achieving control over nanoscale phonon transport. Engineered nanoscale features offer remarkable possibilities to manipulate phonons in nanostructures.

My research program focuses on the central theme of tuning phonons and their interactions with other quantum particles via engineering of nanostructured materials, to enable a broad range of technological applications. However, introduction of structural features affects the transport of other quantum particles because of increased scattering. Our aim is to devise phonon engineering strategies to produce desired transport of quantum particles in nanostructured materials.

In this seminar, I present an overview of the research activities in my group: phonon and electron transport in multilayered Si/Ge nanostructures with defected interfaces, electron-phonon scattering rates in superlattices, guiding phonons in nanostructured membranes though introduction of local resonances, and statistical/machine learning modeling and prediction of charge transport in multilayered semiconductors.

Bio: Sanghamitra Neogi is an assistant professor in the Smead Aerospace Engineering Sciences Department at the University of Colorado, Boulder. Her research focuses on establishing structure-processing-property relationships in nanostructured materials, thermoelectric energy conversion, application of statistical learning methods to predict heat and charge transport in nanostructures, phonon engineering, and probing spin-phonon interaction in quantum systems.