This mini-colloquium will address the subject of controlled disorder in model systems, encompassing a wide range of topics ranging from structural modifications and even transformations to the relation between disorder and dynamic processes. Disorder can arise from variations in composition, as in multicomponent compounds, alloys, and man-made artificial structures introduced by e.g., irradiation, lithography, or other forms of micro- and nano-structuring. The description of systems with coherent and semi-coherent interfaces are clearly also of interest for this mini-colloquium.

Scattering techniques (x-ray, neutron, and electron diffraction) sensitive to charge, nuclear, and magnetic order of a system, as well as spectroscopic techniques measuring the different susceptibilities and the system’s dynamic response are privileged sources of information for describing the characteristics and the influence of disorder on its physical properties. Modelling techniques to predict the structure of the system as a whole, as well as disorder structures and the evolution thereof are also important. Particular emphasis will be on modelling that takes advantage of semi-empirical potentials to describe large systems in which disorder can appear as extended defects.

Static and dynamic disorder have a strong impact on transformation paths and on a host of physical properties. Whereas disorder is usually responsible for unwanted degradation, it sometimes results in dramatic enhancements, as in super-ionic conductors. Problems and opportunities related to the modelling and description of structural defects will be discussed, with references to electrical, optical, mechanical, thermal, conduction, magnetic, and dielectric properties of alloys, semiconductors, superconductors, and insulators.