Optimization of high-temperature superconducting bilayer structures using a vortex dynamics simulation

We argue that the current carrying properties of high-temperature superconducting thin films can be further improved, in particular under the mid-field range (B asymptotic to 0.1-2 T), via introduction of multilayer structures that compromise between good zero field critical current and vortex pinning performance. In this work we focus on a simple bilayer structure consisting of two adjacent layers of pure YBa2Cu3O6+x (YBCO) and BaZrO3 (BZO) doped YBCO under magnetic field within the mid-field range oriented parallel to the c-axis of the YBCO unit cell. We have utilized a computational model to simulate the vortex dynamics limited critical current separately from the associated zero field current, which is addressed analytically. The obtained results have allowed us to estimate the optimal layer thicknesses as a function of magnetic field. Our idealized model suggests that the thickness of the doped layer should be substantially smaller than the undoped one, that is around 30% of the total thickness of the film. We have estimated that the current carrying capability of the optimized bilayer structure can be up to 50% higher when compared with corresponding single layer films. Possible deviations from the obtained results associated with the idealized model, most prominently the effect of natural defects, are comprehensively discussed. Our results provide the foundation for the future experimental realization of the proposed bilayer structures. The comparison between the presented results and experimental realization would enable further study of the underlying primitive vortex interactions.

Automated summary

We propose that the current carrying properties of high-temperature superconducting thin films can be enhanced by introducing multilayer structures that balance zero field critical current and vortex pinning performance. In this study, we investigate a simple bilayer structure composed of pure YBCO and BZO doped YBCO under a mid-field range magnetic field. Our computational model reveals that the optimized bilayer structure can have up to 50% higher current carrying capability compared to single layer films. The results provide a foundation for future experimental realization of the proposed bilayer structures and further study of vortex interactions.