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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.

钇基超导薄膜具有应变对临界电流的可逆影响。然而，这一现象的起源尚未澄清。本文采用四点弯曲法研究了在SrTiO_3单晶衬底上生长的无晶界YBCO薄膜的临界电流随应变的变化规律。结果，对于与实际双轴织构多晶膜类似的单晶膜，确认了在一定施加应变下的临界电流的峰值。这表明晶粒内的晶格变形有助于应变对临界电流以及晶界处的应变的可逆效应。此外，利用同步辐射X射线衍射技术，对不同应变敏感度的Gd基超导薄膜在拉伸载荷下沿沿着a轴和b轴的内部应变变化进行了直接测量。实验结果表明，应变灵敏度小的GdBCO薄膜的[110]方向平行于加载轴，沿a轴和b轴的感应应变沿着方向小于a轴和b轴平行于导体轴和宽度方向的薄膜。结果表明，超导薄膜晶体取向的差异可能是决定临界电流应变依赖性的微观原因之一。