Advantageous grain boundaries in iron pnictide superconductors.
Advantageous grain boundaries in iron pnictide superconductors.
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DOI：
10.1038/ncomms1419
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发表时间：
2011-08-02
影响因子：
16.6
通讯作者：
中科院分区：
文献类型：
--
作者：
高临界温度超导体具有零功耗，可用于生产理想的电力线。制造超导线材和超导带材的主要障碍是晶界--晶界处晶体取向的不对准，这对于多晶体是不可避免的，极大地恶化了临界电流密度。在这里，我们报告说，高临界温度的铁磷属元素化物超导体具有优势，铜酸盐相对于这些晶界问题。系统研究了在双晶衬底上制备的掺钴BaFe_2As_2（BaFe_2As_2：Co）外延薄膜在具有不同取向差角（θGB）的双晶晶界结中的输运性质。通过双晶晶界的临界电流密度（JcBGB）保持很高（>1 MA cm−2），并且在临界角θc为1.9 °时几乎恒定，这比YBa 2Cu 3 O 7-δ的θc为1.5 °大得多。即使在θGB>θc时，JcBGB的衰减也比YBa_2Cu_3O_（7-δ）慢得多。高临界温度超导体可以用来生产理想的电力线，但晶粒边界的错位降低了电流密度。在这里，磷属元素化物超导体被发现是更宽容的错位晶界比铜酸盐。
High critical temperature superconductors have zero power consumption and could be used to produce ideal electric power lines. The principal obstacle in fabricating superconducting wires and tapes is grain boundaries—the misalignment of crystalline orientations at grain boundaries, which is unavoidable for polycrystals, largely deteriorates critical current density. Here we report that high critical temperature iron pnictide superconductors have advantages over cuprates with respect to these grain boundary issues. The transport properties through well-defined bicrystal grain boundary junctions with various misorientation angles (θGB) were systematically investigated for cobalt-doped BaFe2As2 (BaFe2As2:Co) epitaxial films fabricated on bicrystal substrates. The critical current density through bicrystal grain boundary (JcBGB) remained high (>1 MA cm−2) and nearly constant up to a critical angle θc of ∼9°, which is substantially larger than the θc of ∼5° for YBa2Cu3O7–δ. Even at θGB>θc, the decay of JcBGB was much slower than that of YBa2Cu3O7–δ. High critical temperature superconductors could be used to produce ideal electric power lines, but the misalignment of crystalline grain boundaries reduces current density. Here, pnictide superconductors are found to be more tolerant to misaligned grain boundaries than cuprates.
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