סמינר בחומר מעובה: Slow relaxations and memory in disordered mechanical systems

Abstract:

Most everyday materials can be described by a set of numbers that describe their properties – a resistor for example is described by its resistance, a number that is useful in predicting how much current will flow through it under a given voltage. Some materials however, lack this basic characteristic.  Under constant external conditions, their properties can change over many time scales, from fractions of a seconds to weeks and even years, without showing any sign of reaching equilibrium. Such behavior is exhibited in a strikingly similar way by very different systems, from materials such as polymers and glass to properties of interfaces leading to friction and even earthquakes.  Perhaps the only common attribute to all this systems is that they are disordered. Yet, in spite of many studies that have been conducted on these recurring motifs across a broad range of systems, identifying the mechanisms underlying the unusual out-of-equilibrium dynamics of disordered systems remains an outstanding problem in condensed matter physics.

Here, I will describe several disordered soft-matter systems that exhibit a similar repertoire of far-from-equilibrium behavior, including logarithmic relaxation and the ability to hold a memory of previous conditions that can last for hours. At the same time, each one of these systems offers a way to track the evolution of the internal structure, presenting an opportunity to reveal and compare mechanisms across different systems.
 

Seminar Organizer: Prof. Shimshon Barad