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arXiv 2303.04512cond-mat.supr-con
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d波超导体晶格格点模型上的约瑟夫森电流理论

Theory of Josephson current on a lattice model of grain boundary in $d$-wave superconductors

Takashi Sakamori, Satoshi Kashiwaya, Rikizo Yano, Yukio Tanaka, Takafumi Hatano, Keiji Yada

AI总结:

该研究在d波超导体对称[001]倾斜晶界的格点模型中发现费米面折叠导致的独特相位干涉效应,其低倾角区最大约瑟夫森电流抑制强于已有理论,可为阐明晶界输运机制提供指导。

摘要:

明确高临界温度超导体(如铜氧化物和铁基超导体)晶界处临界电流的抑制起源,是多晶材料未来应用中亟待解决的关键问题。尽管电流抑制的主导因素可能源于材料制备和/或加工过程,但研究配对势内部相变导致的电流抑制,对于理解临界电流的阈值是一个重要课题。本文在格点模型上研究了d波超导体对称[001]倾斜晶界(GB)处的约瑟夫森电流。除了连续模型中已预言的、与d波配对势内部相变相关的最大约瑟夫森电流抑制外,我们还发现了格点模型中由费米面折叠导致的独特相位干涉效应。特别是,低倾斜角区域的最终最大约瑟夫森电流往往比已有理论中的结果受到更显著的抑制。由于多项实验工作已报道了晶界处临界电流的类似抑制现象,本模型可作为阐明晶界中复杂输运机制的指导。

英文摘要:

Identifying the origins of suppression of the critical current at grain boundaries of high-critical-temperature superconductors, such as cuprates and iron-based superconductors, is a crucial issue to be solved for future applications with polycrystalline materials. Although the dominant factor of current suppression might arise during material fabrication and/or processing, investigating it due to an internal phase change of the pair potential is an important issue in understanding the threshold of the critical current. In this paper, we study the Josephson current on a symmetric [001]-tilt grain boundary (GB) of a $d$-wave superconductor on a lattice model. In addition to the suppression of the maximum Josephson current associated with the internal phase change of the $d$-wave pair potential which has been predicted in continuum models, we find a unique phase interference effect due to folding of the Fermi surface in the lattice model. In particular, the resultant maximum Josephson current at low-tilting-angle regions tends to be suppressed more than that in preexisting theories. Because similar suppressions of the critical current at GBs have been reported in several experimental works, the present model can serve as a guide to clarify the complicated transport mechanism in GBs.

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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