Epitaxy as a route to understanding quasicrystallinity

One of the emerging research fields in solid-state physics is quasicrystal. Quasicrystals are alloys of specific stoichiometry, which differ from other two known states, crystal and amorphous. They possess aperiodic long range order often associated with crystallographically forbidden rotational symmetries and exhibit many outstanding physical properties. However, the important question are these properties solely related to quasicrystallinity? remains unresolved.This Fellowship proposal aims to resolve this intriguing question by a method of surface science. The surface of quasicrystals will be used as a template to grow pseudomorphic films of a single element. Such films will have quasiperiodic structure but with a reduced chemical complexity compared to the bulk quasicrystals. Thus, these films could potentially be used to study the influence of quasicrystallinity on the associated physical properties, independently of the complex alloy-composition.A promising application of quasicrystals is in catalysis. Because of the complex nature of real world catalysts, it has not been possible to achieve systematic information on the parameters influencing the activity. This proposal plans to study simple and well-defined model catalysts formed by depositing catalytically active metals on single-grain quasicrystal surfaces. Using these systems, catalytic activity can be studied as a function of various parameters on atomic scale in a control way.In addition to the concerns outlined above, use of quasicrystal surface has another interest. Since quasicrystals differ from conventional crystals in various regards such as structure, symmetry, and electronic properties, these parameters of the substrate could result in the development of exotic structures.