Zuo Kun, Mourik Vincent, Szombati Daniel B, Nijholt Bas, van Woerkom David J, Geresdi Attila, Chen Jun, Ostroukh Viacheslav P, Akhmerov Anton R, Plissard Sebastién R, Car Diana, Bakkers Erik P A M, Pikulin Dmitry I, Kouwenhoven Leo P, Frolov Sergey M
QuTech, Delft University of Technology, 2600 GA Delft, Netherlands.
Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, Netherlands.
Phys Rev Lett. 2017 Nov 3;119(18):187704. doi: 10.1103/PhysRevLett.119.187704.
Junctions created by coupling two superconductors via a semiconductor nanowire in the presence of high magnetic fields are the basis for the potential detection, fusion, and braiding of Majorana bound states. We study NbTiN/InSb nanowire/NbTiN Josephson junctions and find that the dependence of the critical current on the magnetic field exhibits gate-tunable nodes. This is in contrast with a well-known Fraunhofer effect, under which critical current nodes form a regular pattern with a period fixed by the junction area. Based on a realistic numerical model we conclude that the Zeeman effect induced by the magnetic field and the spin-orbit interaction in the nanowire are insufficient to explain the observed evolution of the Josephson effect. We find the interference between the few occupied one-dimensional modes in the nanowire to be the dominant mechanism responsible for the critical current behavior. We also report a strong suppression of critical currents at finite magnetic fields that should be taken into account when designing circuits based on Majorana bound states.
在强磁场存在的情况下，通过半导体纳米线耦合两个超导体所形成的结是实现马约拉纳束缚态潜在探测、融合和编织的基础。我们研究了铌钛氮/锑化铟纳米线/铌钛氮约瑟夫森结，发现临界电流对磁场的依赖性呈现出门电压可调的节点。这与著名的夫琅禾费效应相反，在夫琅禾费效应下，临界电流节点形成具有由结面积固定周期的规则图案。基于一个实际的数值模型，我们得出结论，磁场诱导的塞曼效应和纳米线中的自旋轨道相互作用不足以解释所观察到的约瑟夫森效应的演变。我们发现纳米线中少数占据的一维模式之间的干涉是导致临界电流行为的主要机制。我们还报告了在有限磁场下临界电流的强烈抑制，这在基于马约拉纳束缚态设计电路时应予以考虑。
