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Abstract:
For cuprate superconductors, a high critical transition temperature (T-c) can be realized in compounds containing multiple CuO2 layers in the unit cell, while a high critical current density (J(c)) is rarely sustained above liquid nitrogen temperature. The CuBa2Ca3Cu4O10+delta (Cu-1234) superconductors synthesized under high oxygen pressure incredibly exhibit high T-c (similar to 117 K) and high J(c) (>10(4) A/cm(2), 100K) values. Here, the "double high" traits of Cu-1234 were investigated with advanced scanning transmission electron microscopy. It was revealed that ordering vacancies and plate-like 90 degrees microdomains induced efficient microstructure pinning centers that suppressed vortex flux flow and enhanced J(c). Furthermore, metallic charge-reservoir blocks [Ba2CuO3+delta] were composed of unique compressed [CuO6] octahedra, which induced many holes with 2p(z) symmetry that significantly decreased the superconducting anisotropy and dramatically enhanced the interlayer coupling that guaranteed a high J(c). On the other hand, optimally doped CuO2 planes inside the thick superconducting blocks [Ca3Cu4O8] maintained a high Our results are applicable to design and synthesis of new superconductors with "double high" traits.
