Designing high-performance superconductors with nanoparticle inclusions: Comparisons to strong pinning theory
Designing high-performance superconductors with nanoparticle inclusions: Comparisons to strong pinning theory
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DOI：
10.1063/5.0057479
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发表时间：
2021-05
期刊：
影响因子：
6.1
通讯作者：
Sarah C. Jones;M. Miura;Ryuji Yoshida;T. Kato;L. Civale;R. Willa;S. Eley
中科院分区：
文献类型：
--
作者：
Sarah C. Jones;M. Miura;Ryuji Yoshida;T. Kato;L. Civale;R. Willa;S. Eley
在超导体中实现高临界电流的最有希望的途径之一是将分散的非超导纳米颗粒结合到一起以控制涡旋的耗散运动。然而，这些夹杂物减少了总的超导体积，并且可以使夹层超导基质应变，这可以间接地降低Tc。因此，必须在纳米颗粒密度n p和尺寸d之间实现最佳平衡。确定这种平衡需要更好地理解强钉扎理论所描述的涡旋-纳米颗粒相互作用。在这里，我们绘制了在高达35 T的磁场中，临界电流对（Y 0.77，Gd 0.23）Ba 2 Cu 3 O 7 − δ薄膜中纳米颗粒尺寸和密度的依赖性，并将趋势与最近的随时间变化的Ginzburg-Landau模拟结果进行了比较。我们确定依赖于场的临界电流JC（B）和强钉扎理论的期望之间的一致性。具体来说，我们发现J c B − α，其中α随着纳米颗粒密度的增加从0.66减小到0.2，并且随着纳米颗粒尺寸d /λ（归一化为相干长度）大致线性地增加。在高磁场下，临界电流衰减得更快（B − 1），这表明每个纳米粒子都捕获了一个涡旋。当纳米颗粒捕获一个以上的漩涡，一个小的，高场峰值预计在J c（B）。由于缺陷尺寸的分布，这种新的峰值效应在这里仍然没有得到解决。最后，我们揭示了涡旋蠕变速率S对纳米颗粒尺寸和密度的依赖关系大致反映了α的依赖关系，并将我们的结果与强钉扎理论预测的S（T）中的低T非线性进行了比较。
One of the most promising routes for achieving high critical currents in superconductors is to incorporate dispersed, non-superconducting nanoparticles to control the dissipative motion of vortices. However, these inclusions reduce the overall superconducting volume and can strain the interlaying superconducting matrix, which can detrimentally reduce T c . Consequently, an optimal balance must be achieved between the nanoparticle density n p and size d . Determining this balance requires garnering a better understanding of vortex–nanoparticle interactions, described by strong pinning theory. Here, we map the dependence of the critical current on nanoparticle size and density in (Y 0.77 , Gd 0.23 )Ba 2 Cu 3 O 7 − δ films in magnetic fields of up to 35 T and compare the trends to recent results from time-dependent Ginzburg–Landau simulations. We identify consistency between the field-dependent critical current J c ( B ) and expectations from strong pinning theory. Specifically, we find that J c ∝ B − α , where α decreases from 0.66 to 0.2 with increasing density of nanoparticles and increases roughly linearly with nanoparticle size d / ξ (normalized to the coherence length). At high fields, the critical current decays faster ( ∼ B − 1 ), sug-gesting that each nanoparticle has captured a vortex. When nanoparticles capture more than one vortex, a small, high-field peak is expected in J c ( B ) . Due to a spread in defect sizes, this novel peak effect remains unresolved here. Finally, we reveal that the dependence of the vortex creep rate S on nanoparticle size and density roughly mirrors that of α , and we compare our results to low- T nonlinearities in S ( T ) that are predicted by strong pinning theory.