Tailoring supercurrent confinement in tunable superconducting weak links

在这个项目中，我们将通过在双层石墨烯中定制可调的静电收缩来研究扩展的2D超导弱连接中的电流限制。通过这种弱连接的超流将作为一系列限制体系结构的磁场的函数来测量。通过测量临界电流的场依赖关系，我们将确定弱连接几何形状与磁场依赖之间的关系。这种方法将允许我们开发一个模型来确定非均匀弱连接中的超流分布，这到目前为止仍然是一个悬而未决的问题。在双层石墨烯中静电开启带隙的可能性将使我们有机会探索一种可调和可静电整形的纳米级弱连接，我们将基于低欧姆边缘连接的hBN-双层石墨烯-hBN VDW异质结来制备这种弱连接。在异质结构上使用额外的介电层，可以高度灵活地设计任何类型的顶部栅极纳米结构，而不会降低迁移率和接触电阻。除了探索载流子的一维限制外，我们还将在双层石墨烯中实现更复杂的系统，如最近理论上提出的电子干涉仪。

In this project we will study electrical current confinement in extended 2D superconducting weak links by tailoring tunable electrostatic constrictions in bilayer graphene. The supercurrent through such weak links will be measured as a function of the magnetic field for a range of confinement architectures. By measuring the field dependence of the critical current, the Fraunhofer pattern, we will determine the correlation between weak link geometry and the magnetic field dependence. This approach will allow us to develop a model to determine the supercurrent distribution in inhomogeneous weak links, which remains an unresolved problem so far. The possibility to electrostatically open a band gap in bilayer graphene will give us the opportunity to explore a tunable and electrostatically shapeable nanoscale weak link, which we will fabricate based on low-ohmic edge connected hBN-bilayer graphene-hBN vdW heterostructures. The usage of an additional dielectric layer on top of a heterostructure allows the highly flexible design of any kind of top gated nanostructures without degrading mobility and contact resistance. Besides exploring the one-dimensional confinement of charge carriers we will also realize more complex systems in bilayer graphene like electronic interferometers as have recently been theoretically proposed.