Designing high-performance superconductors with nanoparticle inclusions: Comparisons to strong pinning theory

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$^{Z-1}$), suggesting that each nanoparticle has captured a vortex. When nanoparticles capture more than one vortex, a small, high-field peak is expected in Jc(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

Molecular dynamics simulation on a layer-by-layer homoepitaxial growth process of SrTiO3(001)

科研費報告書収録論文(課題番号:09355030・基盤研究(A)(2)・H9～H11/研究代表者:宮本, 明/次世代エレクトロニクス材料としての酸化物人口超格子の原子レベル設計と開発

Layer-by-layer heteroepitaxial growth process of a BaO layer on SrTiO3(001) as investigated by molecular dynamics

科研費報告書収録論文(課題番号:09355030・基盤研究(A)(2)・H9～H11/研究代表者:宮本, 明/次世代エレクトロニクス材料としての酸化物人口超格子の原子レベル設計と開発

Layer-by-layer homoepitaxial growth process of MgO(001)as investigated by molecular dynamics, density functional theory,and computer graphics

科研費報告書収録論文(課題番号:09355030・基盤研究(A)(2)・H9～H11/研究代表者:宮本, 明/次世代エレクトロニクス材料としての酸化物人口超格子の原子レベル設計と開発

Molecular dynamics simulation of enhanced oxygen ion diffusion in strained yttria-stabilized zirconia

科研費報告書収録論文(課題番号:09355030・基盤研究(A)(2)・H9～H11/研究代表者:宮本, 明/次世代エレクトロニクス材料としての酸化物人口超格子の原子レベル設計と開発

A new perfusion culture method with a self-organized capillary network

A lack of perfusion has been one of the most significant obstacles for three-dimensional culture systems of organoids and embryonic tissues. Here, we developed a simple and reliable method to implement a perfusable capillary network in vitro. The method employed the self-organization of endothelial cells to generate a capillary network and a static pressure difference for culture medium circulation, which can be easily introduced to standard biological laboratories and enables long-term cultivation of vascular structures. Using this culture system, we perfused the lumen of the self-organized capillary network and observed a flow-induced vascular remodeling process, cell shape changes, and collective cell migration. We also observed an increase in cell proliferation around the self-organized vasculature induced by flow, indicating functional perfusion of the culture medium. We also reconstructed extravasation of tumor and inflammatory cells, and circulation inside spheroids including endothelial cells and human lung fibroblasts. In conclusion, this system is a promising tool to elucidate the mechanisms of various biological processes related to vascular flow