Rivasto E, Hynninen T, Huhtinen H, Paturi P
Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
University of Turku Graduate School (UTUGS), University of Turku, 20014 Turku, Finland.
J Phys Condens Matter. 2022 Dec 14;35(7). doi: 10.1088/1361-648X/ac9f97.
We argue that the current carrying properties of high-temperature superconducting thin films can be further improved, in particular under the mid-field range ( ≈ 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 YBaCuO6+x(YBCO) and BaZrO(BZO) doped YBCO under magnetic field within the mid-field range oriented parallel to the-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.
我们认为，通过引入在良好零场临界电流和涡旋钉扎性能之间取得折衷的多层结构，可以进一步改善高温超导薄膜的载流特性，特别是在中场范围（≈0.1 - 2 T）内。在这项工作中，我们关注一种简单的双层结构，该结构由两层相邻的纯YBaCuO6+x（YBCO）和掺有BaZrO（BZO）的YBCO组成，处于平行于YBCO晶胞c轴取向的中场范围内的磁场中。我们利用一个计算模型分别模拟了涡旋动力学限制的临界电流与相关的零场电流，后者通过解析方法求解。所得结果使我们能够估计作为磁场函数的最佳层厚度。我们的理想化模型表明，掺杂层的厚度应远小于未掺杂层，约为薄膜总厚度的30%。我们估计，与相应的单层薄膜相比，优化后的双层结构的载流能力可提高多达50%。全面讨论了与理想化模型相关的所得结果可能存在的偏差，最显著的是自然缺陷的影响。我们的结果为未来实验实现所提出的双层结构奠定了基础。将所呈现的结果与实验实现进行比较，将能够进一步研究潜在的原始涡旋相互作用。
