Critical Current Densities through Josephson Junctions in Low Magnetic Fields

Understanding the properties of grain boundaries in polycrystalline superconductors is essential for optimizing their critical current density. Here, we provide computational simulations of 2D Josephson junctions (JJs) in low magnetic fields using time--dependent Ginzburg--Landau theory, since they can be considered a proxy for a grain boundary between two grains. We present data for junctions with a wide range of superconducting electrodes of different Ginzburg--Landau parameter (κ) values and geometries, as well as normal barriers with different strengths of pair--breaking --- characterized by the thickness of the junction and the junction condensation parameter (αn). We describe our results using analytic solutions, and hence provide a detailed description of Josephson junctions in low fields up to that required for a single fluxon to penetrate the junction.

深入解析多晶超导体晶界特性对于优化其临界电流密度至关重要。在本研究中，我们采用时变Ginzburg-Landau理论对低磁场下的二维约瑟夫森结（JJ）进行计算模拟，因其可被视为两晶粒之间晶界的替代物。我们提供了具有广泛超导电极（不同Ginzburg-Landau参数κ值和几何形状）以及不同强度对破缺正常势垒（以结厚度和结凝聚参数αn表征）的结数据。我们通过解析解描述了研究结果，从而对低磁场下直至单个磁通量可以穿透结所需的磁场条件下的约瑟夫森结进行了详细描述。