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Basic study of supemanducting device with asymmetric flux pinning centers

具有不对称磁通钉扎中心的超导装置的基础研究

基本信息

批准号：
18560307
负责人：
HARADA Naoyuki
金额：
$ 2.53万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

The critical current density Jc of type II superconductor is determined by the pinning interaction between flux line lattices and pinning centers. Jc properties are governed by the introduction of artificial pinning centers (APC). Currently, artificial pinning centers have been introduced into metallic superconducting wires through the drawing process to achieve high Jc. On the other hand, a new method using microfabrication to introduce artificial pinning centers into a superconducting film was proposed. In this study, the introduction of asymmetric artificial pinning centers, their behavior under Lorentz force and a new device introduced asymmetric artificial pinning centers were investigated. Using numerical analysis, it was shown that the asymmetric pinning potentials caused by the asymmetric shape of the pinning centers could induce significant asymmetries in the magnetic flux pinning force and the distribution of the critical current density when the polarity of the applied current was changed. In order to investigate the asymmetric properties, step-shaped patterns were introduced as asymmetric artificial pinning centers (APCs) in a 0.5-μm-thick Nb film evaporated on an Al_2O_3 (1102) single crystalline substrate by using a lithographic technique. The patterns had periodic intervals of 4.0-5.0 μm. In addition, instead of the distribution of the critical current density, the distribution of the magnetic flux density in the specimen was directly observed using the magneto-optical imaging method. The asymmetric distribution of the magnetic flux density caused by the asymmetric shape of the APCs was observed by comparing the shift between the position where the magnetic flux density is the lowest and the position where it is the highest using the magneto-optical images. A new device with asymmetric critical current properties would be studied.

II型超导体的临界电流密度Jc由磁通线晶格和钉扎中心之间的钉扎相互作用决定。 Jc 属性由人工钉扎中心 (APC) 的引入控制。目前，已通过拉丝工艺将人工钉扎中心引入金属超导线材中，以实现高Jc。另一方面，提出了一种利用微加工将人工钉扎中心引入超导薄膜的新方法。在这项研究中，研究了不对称人工钉扎中心的引入、它们在洛伦兹力下的行为以及引入不对称人工钉扎中心的新装置。数值分析表明，当施加电流的极性改变时，由钉扎中心的不对称形状引起的不对称钉扎电势会引起磁通钉扎力和临界电流密度分布的显着不对称。为了研究不对称特性，利用光刻技术在 Al_2O_3 (1102) 单晶衬底上蒸发的 0.5 μm 厚 Nb 薄膜中引入阶梯形图案作为不对称人工钉扎中心 (APC)。图案的周期间隔为4.0-5.0μm。此外，利用磁光成像方法直接观察样品中磁通密度的分布，而不是临界电流密度的分布。通过使用磁光图像比较磁通密度最低的位置和最高的位置之间的偏移，观察到由APC的不对称形状引起的磁通密度的不对称分布。将研究一种具有不对称临界电流特性的新器件。