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Microscopic mechanism to determine strain dependence of critical current for Yttrium-based high Tc superconducting film

确定钇基高温超导薄膜临界电流应变依赖性的微观机制

基本信息

批准号：
22760522
负责人：
SUGANO Michinaka
金额：
$ 2.75万
依托单位：
High Energy Accelerator Research Organization (2011)Kyoto University (2010)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Young Scientists (B)
财政年份：
2010
资助国家：
日本
起止时间：
2010 至 2011
项目状态：
已结题

项目摘要

Yttrium-based superconducting film exhibits reversible effect of strain on critical current. However, the origin of this phenomenon has not been clarified. In this study, we succeeded in evaluating strain dependence of critical current in magnetic field for YBCO film without grain boundaries grown on SrTiO_3 single crystal substrate by means of a 4-point bending method. As a result, the peak of the critical current at a certain applied strain was confirmed for a single-crystalline film similar with the practical biaxially-textured polycrystalline film. This suggests that lattice deformation within a grain contributes to the reversible effect of strain on critical current as well as strain at the grain boundaries. In addition, change in internal strain under tensile loading was directly evaluated along a-anb b-axes for Gd-based superconducting films with different strain sensitivity to critical current using synchrotron radiation based on X-ray diffraction technique. This experiment reveals that GdBCO film with small strain sensitivity orients its[110] direction parallel to the loading axis and induced strain along the a-and b-axes is smaller than the other film in which a-and b-axis orients to the conductor axis and width. As a result, it was clarified that difference in crystal orientation of superconducting film can be one of the microscopic origins to determine strain dependence of critical current.

镱基超导薄膜表现出应变对临界电流的可逆效应。然而，这一现象的起源并没有得到澄清。在本研究中，我们利用四点弯曲法成功地评估了SrTiO_3单晶衬底上生长的无晶界YBCO薄膜在磁场中临界电流的应变依赖性。结果表明，在一定的外加应变下，单晶薄膜的临界电流峰值与实际的双轴织构多晶薄膜相似。这表明，晶内的晶格变形有助于应变对临界电流和晶界应变的可逆效应。此外，利用基于x射线衍射技术的同步辐射，直接评估了具有不同应变敏感性临界电流的gd基超导薄膜在拉伸载荷下沿a轴和b轴的内部应变变化。实验表明，应变灵敏度较小的GdBCO薄膜[110]取向方向平行于加载轴，其沿a轴和b轴的诱导应变小于a轴和b轴取向于导体轴线和宽度的其他薄膜。结果表明，超导薄膜的晶体取向差异可能是决定临界电流应变依赖性的微观来源之一。