Physics of Quasicrystals and Their Approximants

凝聚态物理学的进步通常需要发现和开发新材料，以扩展或挑战当前的理解。该提案涉及新材料的合成及其物理性质的研究。该项目的重点是目前感兴趣的一类特殊材料，即准晶体。准晶发现于1984年，是一种新的固体形式，不同于其他两种类型，晶体和非晶，通过拥有一种新的长程有序，称为准周期性，以及与经典禁止的五重，八重，十重和十二重对称轴相关的非晶体学取向顺序。凝聚态物理学的中心问题之一是准周期性是否会导致与晶体和非晶体材料显著不同的新物理性质。这个提议将试图通过回答关于准晶的磁性和电子结构性质的几个突出问题来发现这种新的性质。这些问题将通过合成许多新的准晶和它们的近似物（具有与准晶相似的局部原子结构的晶体材料）以及用一系列现代实验技术研究它们的磁性和电子结构特性来解决。该提案的预期成果将是对这些新材料的基本物理特性的全面了解。该项目的实现不仅有利于凝聚态研究领域，而且可能会发现准周期性诱导的准晶在材料工业中的应用。此外，大约20多名高素质人员将获得一系列实用的综合和测量技能，这将有助于他们在工业或学术界的高技术部门就业。

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.