The Origins of Microstructure: Dynamics and Patterning of Topological Defects in Soft and Hard Condensed Matter – Robin Selinger

Date: Thu. September 29th, 2005, 4:15 pm-5:15 pm
Location: Rockefeller 301

Most condensed matter is riddled with defects that interrupt long-range order. Your house key, for instance, contains a network of grain boundaries and dislocations without which it would be too soft to hold its shape. Microstructure, the spatial arrangement of structural defects, both controls mechanical response and strongly affects transport properties. Understanding microstructure’s formation and evolution is a central goal of materials science research.

Defect-rich structures represent metastable states in most materials, and a sample will relax toward more complete long-range order when annealed. But curiously, there are many soft materials in which a defect-rich structure persists even in thermal equilibrium. Understanding these complex phases is a central goal of soft condensed matter theory.

As a researcher working in both materials science and soft condensed matter, I use simulation techniques to explore the nucleation, motion, and (sometimes) pattern formation of topological defects both in crystalline solids and in liquid crystals. Using simulation techniques ranging from the molecular to the mesoscale, I’ll explore a variety of phenomena including plastic deformation and fracture of metals, and phase behavior and transport properties in smectic liquid crystals. In each case I’ll focus on the crucial role played by defects, and on what scientists in these two research fields can learn from one another.