MMAE Seminar - Dr. David G. Cahill - Ultrafast Heat Transfer in Nanoscale Materials

Armour College of Engineering's Mechanical, Materials & Aerospace Engineering Department will welcome Dr. David Cahill, the Willett Professor and Department Head of Materials Science and Engineering at the University of Illinois at Urbana-Champaign, to present his lecture, Ultrafast Heat Transfer in Nanoscale Materials.

Abstract

On the macroscopic lengths scales of conventional engineering systems, heat transfer by conduction is generally a slow process well-described by the heat diffusion equation. The characteristic time-scale of diffusion scales with the square of length; therefore, at nanometer length scales, heat conduction can involve processes that occur on time-scales of picoseconds, i.e., a few trillionth of a second. We use ultrafast pump-probe optical techniques to directly study a variety of unconventional heat transfer mechanisms that are critical in nanoscale devices and nanoscale materials. Our studies encompass a diverse variety of systems (metallic nanoparticles for photothermal medical therapies, phase change materials for solid-state memory, and heat-assisted magnetic recording) and physical mechanisms (the thermal conductance of interfaces between dissimilar materials, the non-equilibrium between thermal excitations of electrons, phonons, and magnons, and the cross-terms in the transport of heat, charge, and spin). In this talk I will highlight three recent examples: i) ultrafast thermal transport in the surroundings of plasmonic nanostructures; ii) limitations on ultrafast heating of metallic multilayers imposed by electron-phonon coupling; and iii) the generation of currents of magnetization by the spin-dependent Seebeck effect and extreme heat fluxes exceeding 100 GW m-2.

Biography

David Cahill is the Willett Professor and Department Head of Materials Science and Engineering at the University of Illinois at Urbana-Champaign. He joined the faculty of the U. Illinois after earning his Ph.D. in condensed matter physics from Cornell University, and working as a postdoctoral research associate at the IBM Watson Research Center. His research program focuses on developing a microscopic understanding of thermal transport at the nanoscale; the discovery of materials with enhanced thermal function; the interactions between phonons, electrons, photons, and spin; and advancing fundamental understanding of interfaces between materials and water. He received the 2018 Innovation in Materials Characterization Award of the Materials Research Society (MRS); the 2015 Touloukian Award of the American Society of Mechanical Engineers; the Peter Mark Memorial Award of the American Vacuum Society (AVS); and is a fellow of the MRS, AVS, and APS (American Physical Society).