YBCO step-edge junctions with high IcRn
YBCO step-edge junctions with high IcRn
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DOI：
10.1088/0953-2048/23/6/065007
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发表时间：
2010-06
影响因子：
3.6
通讯作者：
E E Mitchell-E;C. Foley
中科院分区：
文献类型：
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作者：
E E Mitchell-E;C. Foley
阶边结代表了高温超导结技术中采用的一种晶界约瑟夫森结。迄今为止，文献中发表的大多数结果集中在[001]-倾斜晶界结（GBJ）使用双晶体衬底生产。我们研究了MgO [001]衬底上YBCO基台阶边缘结的台阶形貌和YBCO（钇钡铜氧化物）薄膜结构，这种结的结构类似于[100]倾斜结。高分辨电子显微镜显示了一个干净的GBJ接口的宽度为1 nm和一个单一的结在顶部边缘。在4.2 K下检查MgO阶边和结形态上的输运性质的依赖性，以便与其他结研究的结果进行直接比较，例如[001]-倾斜和[100]-倾斜结，并建立在先前发表的77 K数据上。MgO阶边结与[001]-倾斜结相比，临界电流密度随阶跃角的降低较慢。对于优化的步骤参数，输运测量显示大的临界电流和正常电阻（IcRN）产品（103 -5 mV），在4.2 K的YBCO中的其他类型的[100]-倾斜GBJ中获得的最佳结果相媲美。当使用MgO基台阶边缘结时，基于结的器件如SQUID（超导量子干涉器件）和THz成像器显示出优异的性能。
Step-edge junctions represent one type of grain boundary Josephson junction employed in high-temperature superconducting junction technology. To date, the majority of results published in the literature focus on [001]-tilt grain boundary junctions (GBJs) produced using bicrystal substrates. We investigate the step morphology and YBCO (yttrium barium copper oxide) film structure of YBCO-based step-edge junctions on MgO [001] substrates which structurally resemble [100]-tilt junctions. High-resolution electron microscopy reveals a clean GBJ interface of width ∼ 1 nm and a single junction at the top edge. The dependence of the transport properties on the MgO step-edge and junction morphology is examined at 4.2 K, to enable direct comparison with results for other junction studies such as [001]-tilt and [100]-tilt junctions and building on previously published 77 K data. MgO step-edge junctions show a slower reduction in critical current density with step angle compared with [001]-tilt junctions. For optimized step parameters, transport measurements revealed large critical current and normal resistance (IcRN) products (∼3–5 mV), comparable with the best results obtained in other kinds of [100]-tilt GBJs in YBCO at 4.2 K. Junction-based devices such as SQUIDs (superconducting quantum interference devices) and THz imagers show excellent performance when MgO-based step-edge junctions are used.