Andreev bound states and their signatures
Andreev bound states and their signatures
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DOI：
10.1098/rsta.2018.0140
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发表时间：
2018-05
期刊：
影响因子：
--
通讯作者：
J. Sauls
中科院分区：
文献类型：
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作者：
J. Sauls
当超导状态被迫响应外部磁场，接近性接触，与铁磁铁的界面或嵌入超级导体中的异质性时，与量子相干性相关的超导体的许多特性都会在空间上变化例如，在强烈不均匀性的区域中，电子在正常驱动的界面上的Andreev反射到反射孔中。动态扩展了分支转换散射和Andreev结合状态的重要性。本文介绍了Andreev散射的基本物理，界限形成及其签名。该目标既适用于该领域中尚未成为专家的有趣读者的介绍，又强调了分支转换散射的示例界面在超导体的运输属性中提供了独特的签名。
Many of the properties of superconductors related to quantum coherence are revealed when the superconducting state is forced to vary in space in response to an external magnetic field, a proximity contact, an interface to a ferromagnet or to impurities embedded in the superconductor. Among the earliest examples is Andreev reflection of an electron into a retro-reflected hole at a normal-superconducting interface. In regions of strong inhomogeneity, multiple Andreev reflection leads to the formation of sub-gap states, Andreev bound states, with excitation energies below the superconducting gap. These states play a central role in our understanding of inhomogeneous superconductors. The discoveries of unconventional superconductivity in many classes of materials, advances in fabrication of superconducting/ferromagnetic hybrids and nanostructures for confining superfluid 3 He, combined with theoretical developments in topological quantum matter have dramatically expanded the significance of branch conversion scattering and Andreev bound state formation. This collection of articles highlights developments in inhomogeneous superconductivity, unconventional superconductivity and topological phases of superfluid 3 He, in which Andreev scattering and bound states underpin much of the physics of these systems. This article provides an introduction to the basic physics of Andreev scattering, bound-state formation and their signatures. The goal is both an introduction for interested readers who are not already experts in the field, and to highlight examples in which branch conversion scattering and Andreev bound states provide unique signatures in the transport properties of superconductors. This article is part of the theme issue ‘Andreev bound states’.