School Of Physics Fall Colloquium Series-Dr. Heinrich Jaeger

Speaker: Heinrich Jaeger (U Chicago)

Host: Zeb Rocklin

Title: Acoustically Levitated Granular Matter

Abstract: An intense ultrasound field can be used not only to levitate particles and manipulate their positions, but sound scattered off individual solid objects gives rise to tunable forces that acoustically bind the particles into larger aggregates. For levitation in air, furthermore, the small viscosity makes it possible to explore the regime of underdamped dynamics in a strongly coupled multi-particle system far-from-equilibrium. I will discuss recent experiments that exploit acoustic levitation to self-assemble small particles into monolayer rafts freely floating in air, while tracking their dynamics with high-speed video imaging. By changing the interparticle spacing and controlling the acoustic energy density, the rafts can transform from close-packed solids into soft lattices that can ‘melt’ into 2D liquids and eventually expand into 3D particle swarms. Along the way, acoustically levitated granular matter provides an exciting new platform to study non-reciprocal multibody forces and the emergent dynamical behavior they can generate.

Bio: Heinrich Jaeger is the Sewell Avery Distinguished Service Professor of Physics at the University of Chicago. He received his Ph.D. in physics in 1987 from the University of Minnesota and has been on the faculty at U Chicago since 1991, directing the Chicago Materials Research Center from 2001 – 2006, and the James Franck Institute from 2007-2010. Jaeger’s current research focuses on self-assembled nanoparticle-based structures, on the rheology of concentrated particle suspensions, and on studies of the flow and jamming properties of granular materials.