Studies of quasicrystals and their approximants

点击翻译按钮获取中文摘要

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 proposal is concerned with one specific class of materials that are of current interest, namely quasicrystals. Discovered in 1984, quasicrystals are a new form of solid that differs from the two other forms, crystalline and amorphous, by possessing a new type of long-range order, called quasiperiodicity, and noncrystallographic orientational order associated with classically forbidden fivefold, eightfold, tenfold, and twelvefold symmetry axes. One of the central problems in condensed matter physics is determining 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 experimentally answering four outstanding questions of the physics of quasicrystals. What types of long-range quasiperiodic magnetic order are realized in quasicrystals? Is the predicted fine structure of the electronic density of states realized in quasicrystals? Are the extremely large values of the electrical resistivity and its nonmetallic temperature dependence the intrinsic properties of quasicrystals? Is theory capable of predicting new quasicrystals with specific physical properties? This proposal will address these four outstanding questions via the synthesis of several families of new quasicrystals and corresponding crystalline approximants and the investigation of their magnetic, electronic structure, and electronic transport properties with an array of modern experimental techniques. The end product of this proposal will be a much clearer and more complete understanding of the basic physical properties of these new materials, that may possibly lead to finding industrial applications of quasicrystals. In addition, a dozen highly qualified personnel will acquire a range of practical synthesis and measurement related skills that will help them to find employment in the high-technology sector of Canadian industry or in academia.