Inversion and time reversal are essential symmetries for the structure of Cooper pairs in superconductors. The loss of one or both leads to modifications to this structure and can change the properties of the superconducting phases in profound ways. Superconductivity in materials lacking inversion symmetry, or noncentrosymmetric materials, has become an important topic. These materials show unusual magnetic and magnetoelectric properties and can host topological superconductivity. Recently, crystal structures with local, but not global, inversion-symmetry breaking have attracted attention. Here, superconductivity can exhibit phenomena not naively expected in centrosymmetric materials. In this review, we first introduce the concept of locally noncentrosymmetric crystals and different material realizations. We then discuss consequences of such local symmetry breaking on the normal state electronic structure and the classification of superconducting order parameters. Finally, we review the expected and, in parts, already observed phenomenology of unconventional superconductivity and possible topological superconducting phases.

中文翻译：

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超导性和局域反演对称性破缺


反演和时间反演是超导体库珀对结构的基本对称性。一种或两种的损失会导致这种结构的改变，并且可以深刻地改变超导相的性质。缺乏反演对称性的材料或非中心对称材料的超导性已成为一个重要的课题。这些材料表现出不寻常的磁性和磁电特性，并且可以具有拓扑超导性。最近，具有局部而非全局反演对称破缺的晶体结构引起了人们的关注。在这里，超导性可以表现出中心对称材料中未曾天真地预期的现象。在这篇综述中，我们首先介绍局部非中心对称晶体的概念和不同的材料实现。然后我们讨论这种局域对称性破缺对正常态电子结构和超导有序参数分类的影响。最后，我们回顾了预期的以及部分已经观察到的非常规超导现象学和可能的拓扑超导相。