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arXiv 2103.15809cond-mat.supr-con
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无场约瑟夫森二极管的实现

Realization of the field-free Josephson Diode

Heng Wu, Yaojia Wang, Yuanfeng Xu, Pranava K. Sivakumar, Chris Pasco, Ulderico Filippozzi, Stuart S. P. Parkin, Yu-Jia Zeng, Tyrel McQueen, Mazhar N. Ali

备注：
30 pages, 14 figures
发表信息：
Nature 604, 653-656 (2022)
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摘要：

超导类似于半导体二极管，约瑟夫森二极管，长期以来一直在寻找，理论家提出了多种实现途径。它展示了无磁场的单向超导性，超导电流通过隧道势垒的约瑟夫森耦合，它将成为下一代超导电路技术的基石。在这里，我们实现了无场约瑟夫森二极管使用反转对称破缺异质结的$\mathrm{NbSe_2/Nb_3Br_8/NbSe_2}$。我们首次证明了在没有磁场的情况下，结可以在一个方向上超导，而在相反的方向上正常。在此基础上，实现了方波激励的半波整流，具有低开关电流密度（$~2.2\times 10^2 \mathrm{A/cm^2}$）、高整流比（$~10^4$）和高鲁棒性（至少$10^4$周期）。我们还证明了对称的$ΔI_\mathrm{c}$（正负临界电流之间的差异）的行为与字段和预期的夫琅和费电流相位关系的约瑟夫森结。这一认识提出了关于对称性破坏时绝缘体的约瑟夫森效应的基本问题，并为逻辑和信号调制打开了超低功耗，高速超导电路的大门。

英文摘要：

The superconducting analog to the semiconducting diode, the Josephson diode, has long been sought, with multiple avenues to realization proposed by theorists. Exhibiting magnetic-field free, single directional superconductivity with Josephson coupling of the supercurrent across a tunnel barrier, it would serve as the building-block for next-generation superconducting circuit technology. Here we realized the field-free Josephson diode using an inversion symmetry breaking heterostructure of $\mathrm{NbSe_2/Nb_3Br_8/NbSe_2}$. We demonstrate, for the first time without magnetic field, the junction can be superconducting in one direction while normal in the opposite direction. Based on that, half-wave rectification of a square-wave excitation was achieved with low switching current density ($~2.2\times 10^2 \mathrm{A/cm^2}$), high rectification ratio ($~10^4$) and high robustness (at least $10^4$ cycles). We also demonstrate symmetric $ΔI_\mathrm{c}$ (the difference between positive and negative critical currents) behavior with field and the expected Fraunhofer current phase relation of a Josephson junction. This realization raises fundamental questions about the Josephson effect through an insulator when breaking symmetry, and opens the door to ultralow power, high speed, superconducting circuits for logic and signal modulation.

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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