arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2006.10073cond-mat.supr-concond-mat.str-el
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自旋极化超导电性:序参量拓扑、电流耗散和多周期约瑟夫森效应

Spin-polarized superconductivity: order parameter topology, current dissipation, and multiple-period Josephson effect

Eyal Cornfeld, Mark S. Rudner, Erez Berg

摘要:

我们讨论了完全自旋极化的三重态超导体的输运性质,其中只有一个自旋分量(沿某一轴)的电子配对。由于序参量空间的结构,其中相位和自旋旋转交织在一起,超导相位在空间中缠绕$4π$的配置在拓扑上等效于没有相位缠绕的配置。这开启了通过序参量的平滑变形的超电流弛豫的可能性,其中在整个过程中,序参量在空间中的任何点处保持非零。在该过程中,形成自旋织构。我们讨论了这些过程发生的条件及其物理后果。特别是,我们表明,当施加电压时,它们会导致一个不寻常的交流约瑟夫森效应,其周期是通常的约瑟夫森周期的整数倍。这些结论在一个简单的含时Ginzburg-Landau模型的序参量动力学中得到了证实。我们的分析的潜在应用之一是莫尔系统,如扭曲的双层和双双层石墨烯,其中超导性被发现在铁磁性附近。

英文摘要:

We discuss transport properties of fully spin-polarized triplet superconductors, where only electrons of one spin component (along a certain axis) are paired. Due to the structure of the order parameter space, wherein phase and spin rotations are intertwined, a configuration where the superconducting phase winds by $4π$ in space is topologically equivalent to a configuration with no phase winding. This opens the possibility of supercurrent relaxation by a smooth deformation of the order parameter, where the order parameter remains non-zero at any point in space throughout the entire process. During the process, a spin texture is formed. We discuss the conditions for such processes to occur and their physical consequences. In particular, we show that when a voltage is applied, they lead to an unusual alternating-current Josephson effect whose period is an integer multiple of the usual Josephson period. These conclusions are substantiated in a simple time-dependent Ginzburg-Landau model for the dynamics of the order parameter. One of the potential applications of our analysis is for moiré systems, such as twisted bilayer and double bilayer graphene, where superconductivity is found in the vicinity of ferromagnetism.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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