Cyclic Memories in Disordered Matter

Cyclic Memories in Disordered Matter
Nathan Keim, Pennsylvania State University, Department of Physics
Prof. Nathan Keim
Date and time: Thu, Feb 20, 2020 - 11:30am
Refreshments at 11:15am
Location: LGRT 1033
Category: Condensed Matter Seminar

Cyclic driving happens all around us. Buildings and bridges are repeatedly loaded and unloaded, and many organisms synchronize their functions with day and night. This kind of driving can change a material, and even form memories that can be recalled later. I present two examples of materials that, when deformed repeatedly, can "learn" and report the magnitudes of those deformations: a suspension of particles in liquid, and a jammed amorphous solid. These exemplify two different but generic ways that non-equilibrium systems can form memories, with suspensions sharing their behavior with charge-density wave conductors, and amorphous solids approximating the return-point behavior best known in magnetic materials. Memory formation offers a new perspective on these and other systems' non-equilibrium natures, and illuminates the benefits of disorder and noise.