Theory of noncentrosymmetric and other unconventional superconductors

现代技术的主要推动力之一是对新材料的研究。超导体是一种可以在没有任何能量损失的情况下导电的材料，特别重要。目前研究的焦点中的大多数超导材料属于非常规超导体的类别，其中高温铜酸盐和铁磷属元素化物、锶铼酸盐、重费米子和有机化合物是一些例子。如果超导体的性质不能用超导的标准模型来解释，特别是巴丁-库珀-施里弗理论，那么超导体就被认为是“非常规的”。 这项研究计划的主要目的是从微观和现象学两方面更好地理解没有反转对称的超导体和其他“拓扑超导体”等有趣的新材料，以及具有复杂电子结构（例如多带电子结构）的晶体中的超导性。即使在传统的超导体中，超越巴丁-库珀-施里弗理论的领域也常常揭示出有趣而丰富的物理学。例如，理解非均匀超导相的非平衡性质需要新的思想和理论技术。我们希望这项研究的结果将为复杂的超导和超流体系统的物理学提供见解。拟议活动产生的更广泛影响将是通过接触当代凝聚态物理学的各种思想和方法，培训新一代高素质人员。

One of the main driving forces of modern technology is the research into new materials. Superconductors, which are the materials that can conduct electricity without any energy losses, are of particular importance. The majority of superconducting materials at the focus of current research belong to the class of unconventional superconductors, with high-temperature cuprates and iron pnictides, strontium ruthenate, heavy-fermion and organic compounds being some of the examples. Superconductors are said to be "unconventional" if their properties cannot be explained by the standard models of superconductivity, in particular, the Bardeen-Cooper-Schrieffer theory. The main objective of this research proposal is to better understand, both microscopically and phenomenologically, such interesting novel materials as superconductors without inversion symmetry and other "topological superconductors", and also superconductivity in crystals with a complicated, e.g. multiband, electronic structure. Even in conventional superconductors, going beyond the domain of the Bardeen-Cooper-Schrieffer theory often reveals an interesting and rich physics. For instance, understanding the nonequilibrium properties of nonuniform superconducting phases requires new ideas and theoretical techniques. We hope that the results of this research will provide insight into the physics of complex superconducting and superfluid systems. The broader impact resulting from the proposed activity will be training of a new generation of highly qualified personnel through an exposure to a wide range of ideas and methods of contemporary condensed matter physics.