Physics of Quasicrystals and Their Approximants

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Advances in condensed matter physics often require the discovery and development of new materials that extend or challenge the current understanding. This proposal addresses both the synthesis of new materials and the investigation of their physical properties. The project is focused on0 one particular class of materials that is of current interest, namely quasicrystals. Discovered in 1984, quasicrystals are a new form of solid that differs from the two other types, crystalline and amorphous, by possessing a new kind of long-range order, called quasiperiodicity, and non-crystallographic orientational order associated with classically forbidden fivefold, eightfold, tenfold, and twelvefold symmetry axes. One of the central problems in condensed-matter physics is whether quasiperiodicity leads to novel physical properties which are significantly different from those of crystalline and amorphous materials. This proposal will attempt to discover such novel properties by answering several outstanding questions concerning the magnetic and electronic structure properties of quasicrystals. These questions will be addressed via the synthesis of many families of new quasicrystals and their approximants (the crystalline materials with a local atomic structure similar to that in quasicrystals) and the investigation of their magnetic and electronic structure properties with an array of modern experimental techniques. The anticipated outcome of this proposal will be a complete understanding of the fundamental physical properties of these new materials. The realization of this project will not only benefit the condensed-matter research field but may lead to finding quasiperiodicity-induced applications of quasicrystals in materials industry. Also, about two dozens of highly qualified personnel will acquire a range of practical synthesis and measurement skills that will help them to find employment in the high-technology sector of industry or academia.