Periodic micron-size flux pinning centers on superconducting Nb films by lithographic techniques
Periodic micron-size flux pinning centers on superconducting Nb films by lithographic techniques
复制标题
通过光刻技术将周期性微米级通量钉扎在超导铌薄膜上
DOI：
10.1109/77.919896
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发表时间：
2001
影响因子：
1.8
通讯作者：
T. Hamajima
中科院分区：
文献类型：
--
作者：
H. Yamada;N. Harada;T. Iwamoto;M. Tsuda;T. Hamajima
众所周知，在NbTi丝中人工钉扎中心对改善超导体的性能是有效的。为了开发高温超导体(HTS)类银套Bi2223薄带材的人工钉扎中心，我们提出了在HTS带材上刻槽和打孔的方案。作为第一步，我们在Nb薄膜上形成周期性的凹槽和孔洞，以代替高温超导，以建立一种制备技术并展示人工钉扎中心的性能。用光刻技术在薄膜上投射和刻蚀出周期间隔为4个/SPLµ/m、深度为0.6~0.9个/SPLµ/m的凹槽和孔洞图案。利用SQUID磁强计对制备的Nb薄膜的性能进行了测试。有花纹的Nb薄膜的临界温度约为9.3K，上临界场为0.45~0.5T。有花纹的Nb薄膜的磁化强度大于无花纹的Nb薄膜。此外，还观察到钉扎力在与磁通晶格间距匹配的外加磁场中共振，在接近临界温度的9.10-9.15K之间。这些结果表明，Nb薄膜上的凹槽和孔洞图案对提高钉扎力是有益的。
It is well known that artificial pinning centers in NbTi filaments are effective for improvement of superconductor performances. In order to develop the artificial pinning centers for a high temperature superconductor (HTS) like Ag-sheathed Bi-2223 thin tape, we proposed groove and hole patterns on the HTS tape. As a first step, we formed periodical grooves and holes on Nb films instead of the HTS to establish a fabrication technique and to demonstrate performances of the artificial pinning centers. The groove and hole patterns with 4 /spl mu/m periodical intervals and 0.6 to 0 9 /spl mu/m in depth were projected and etched on the film with a photolithographic technique. The properties of the fabricated Nb films with the patterns were measured with a SQUID magnetometer. The Nb films with the patterns have critical temperature around 9.3 K and upper critical field of 0.45-0.5 T. The measured magnetizations of the Nb films with the patterns were larger than those of the films without the patterns. It was, moreover, observed that the pinning forces were resonated at applied magnetic field matching with flux lattice spacing at 9.10-9.15 K close to the critical temperature. These results demonstrate that the groove and hole patterns on the Nb films are useful for the improvement of pinning force.