||Mission Statement: The purpose of this symposium is to bring to the fore very recent and exciting developments related to frustration (i.e.the onset of a glassy-like state) of ferroic degrees of freedom (strain, polarization, magnetization) that result from the interplay between disorder and phase instability. The symposium will bring together experts in the theory, simulation and experimental characterization of frustration in different classes of functional materials. The ultimate goal of the present symposium is to discover commonalities as well as key differences in the underlying physics responsible for the frustration of ferroic phase transitions as a way to better understand and exploit these phenomena.
There exists a broad class of functional materials where interplay of disorder and phase instability “frustrates” the active phase transition resulting in the formation of inhomogeneous nanoregions and frequency dependent relaxation behavior. Relaxor ferroelectrics, which are currently utilized in medical ultrasonics and military sonar, develop electrically polar nanoregions hundreds of degrees above the expected ordering temperature. Fluctuations of these polar nanoregions are also thought to be responsible for the frequency dependent relaxation behavior.
More recently, a new class of shape memory alloys, commonly called “strain glasses”, has emerged with behavior that in many respects parallels the classic relaxor ferroelectrics. For example, they exhibit precursor nanoregions and frequency dependent relaxation behavior. Furthermore, the displacive “parent” transitions in both cases exhibit soft-phonon precursors. The experimental approaches and model construction for both problems also have considerable overlap, although there are fundamental differences related to the nature and behavior of the ‘quenched’ random fields that are theorized to be responsible for the slow relaxation behavior.
In the case of relaxor ferroelectrics, the general picture of how polar nanoregions become quenched by interacting with the random electric field is built on an analogy with magnetic spin glasses. Similar models have been put forward to explain frustration in their strain glass counterparts. Thus, studies of magnetic frustrated systems can shed light on the nature of the other frustrated ferroic states.
Description of Symposium:
In this symposium, we propose to bring together different facets of this topic together in a single symposium that includes four distinct sessions over a two-day period:
1. General theory of frustration
2. Relaxor Ferroelectrics
3. Strain Glasses
4. Magnetic Glasses
The sessions are expected to consist of invited and contributed talks on theoretical, computational and experimental aspects of frustration in ferroic systems and will include works on the phase stability, kinetics, relaxation behavior as well as the effect of frustration on the functional properties of the materials.