近日，德国柏林自由大学的Katharina J.Franke及其团队探究了单磁原子约瑟夫森结中的二极管效应。相关成果已于2023年3月8日在国际权威学术期刊《自然》上发表。

该团队利用扫描隧道显微镜中创建了原子级的Pb-Pb约瑟夫森结来研究微型化的极限。由单个Pb原子稳定的原始结表现出迟滞行为，证实了结的高质量，但没有偏置方向之间的不对称性。当将单个磁原子插入结中时，会出现易磁化方向取决于原子种类的非互易超电流。在理论建模的帮助下，研究人员追踪了超导能隙内电子空穴不对称Yu-Shiba-Rtheminov态流动的准粒子电流的非互易性，并确定了约瑟夫森结中二极管行为的新机制。他们的研究结果为创建原子级的约瑟夫森二极管并通过单原子操纵调节其特性开辟了新的途径。

据介绍，电子器件中的电流流动可能存在偏向一方的非对称性，这种现象构成了二极管的实用基础，被称为非互易电荷传输。无耗散电子的前景最近激发了对超导二极管的追求，而非互易超导器件已在各种非中心对称系统中实现。

附：英文原文

Title: Diode effect in Josephson junctions with a single magnetic atom

Author: Trahms, Martina, Melischek, Larissa, Steiner, Jacob F., Mahendru, Bharti, Tamir, Idan, Bogdanoff, Nils, Peters, Olof, Reecht, Gal, Winkelmann, Clemens B., von Oppen, Felix, Franke, Katharina J.

Issue&Volume: 2023-03-08

Abstract: Current flow in electronic devices can be asymmetric with bias direction, a phenomenon underlying the utility of diodes and known as non-reciprocal charge transport. The promise of dissipationless electronics has recently stimulated the quest for superconducting diodes, and non-reciprocal superconducting devices have been realized in various non-centrosymmetric systems. Here we investigate the ultimate limits of miniaturization by creating atomic-scale Pb–Pb Josephson junctions in a scanning tunnelling microscope. Pristine junctions stabilized by a single Pb atom exhibit hysteretic behaviour, confirming the high quality of the junctions, but no asymmetry between the bias directions. Non-reciprocal supercurrents emerge when inserting a single magnetic atom into the junction, with the preferred direction depending on the atomic species. Aided by theoretical modelling, we trace the non-reciprocity to quasiparticle currents flowing by means of electron–hole asymmetric Yu–Shiba–Rusinov states inside the superconducting energy gap and identify a new mechanism for diode behaviour in Josephson junctions. Our results open new avenues for creating atomic-scale Josephson diodes and tuning their properties through single-atom manipulation.

DOI: 10.1038/s41586-023-05743-z

Source: https://www.nature.com/articles/s41586-023-05743-z