Study of high current density superconducting conductor introduced by microfabrication technique.

用于电力电缆和高场磁体的实用超导导线需要高临界电流密度。有效的磁通钉扎中心的发展，这些实用的超导体，以实现高的临界电流密度。在金属超导体的情况下，拉制过程在金属超导体中引入人工钉扎中心。然而，人工钉扎中心不能通过拉伸过程引入到高Tc超导体中，因为这些超导体是脆性的。我们考虑微加工技术，而不是拉伸过程中，为了引入人工钉扎中心的超导体。采用光刻法在MgO衬底或蓝宝石衬底上的0.22-0.5μm蒸镀Nb膜中引入沟槽状人工钉扎中心和孔洞状人工钉扎中心。通过刻蚀在Nb膜的0.9 × 0.9mm区域上引入了两种间距为2μm和4μm的槽形图案。制备了不同槽深的Nb薄膜，并研究了槽深对临界电流密度的依赖关系，得到了磁矩磁滞曲线的宽度。用SQUID磁强计测量了带槽试样的磁滞曲线。滞后曲线的宽度随着槽深的增加而减小，超过70%的膜厚。

Practical superconducting wires for power cables and high field magnets require a high critical current density. Effective flux pinning centers are required for the development of these practical superconductors in order to achieve high critical current density. In the case of metallic superconductors, a drawing process introduces artificial pinning centers in metallic superconductors. However, artificial pinning centers cannot be introduced into high-Tc superconductors through the drawing process because these superconductors are brittle. We consider the microfabrication technique, instead of the drawing process, in order to introduce artificial pinning centers into the superconductors. Groove-shaped artificial pinning centers and hole-shaped artificial pinning centers are introduced into 0.22-0.5μm thick evaporated Nb film on a MgO substrate or a sapphire substrate by photolithography. The groove-shaped patterns with two kind of spacing of 2μm and 4μm were introduced by etching on a 0.9 × 0.9mm region of the Nb film. Nb films with varying groove depths were prepared, and the groove depth dependence on critical current density was investigated for the width of the hysteresis curve of the magnetic moment. The hysteresis curves of the specimens with grooves were measured with a SQUID magnetometer. The width of the hysteresis curve decreases with an increasing groove depth for over 70% of the film thickness.