Ultrasonic Excitation of Magnetic Flux Flow in Multilayered Thin Films of Superconductor-Piezoelectric Material

这个项目被定为两年计划。然而，由于激光烧蚀设备的制造从最初的计划延迟，多层薄膜的制备没有成功。在平行的制造，BiSrCaCuO薄膜的制备使用直流溅射，并通过超声激发的磁通流电压进行了测量。实验结果为超导-压电材料薄膜的测量提供了一定的参考。研究了缓冲层对BiSrCaCuO层结晶性和超导电性的影响，以获得高质量的薄膜。研究发现，缓冲层的存在减小了薄膜与衬底晶格失配引起的应变，提高了超导转变温度和薄膜表面的粗糙度.测量了上述薄膜和烧结体样品在纵向超声激励下的磁通流电压。将实验结果与基于热辅助磁通流动模型的理论计算结果进行了比较，并指出了有待解决的问题.磁通流电压的测量与不同的振动模式的超声波，这是有关的熔化的磁通线晶格。磁通流动电压的特征现象进行了观察。

This project was schemed as a two-year plan. However, the preparation of multilayered thin films was not succeeded, because the fabrication of the equipment of the laser ablation was delayed from the initial plan. In parallel to the fabrication, BiSrCaCuO thin films were prepared using a dc sputtering, and the flux flow voltage excited by ultrasound was measured. The experimental results which will give some information for the measurements using thin films of superconductor-piezoelectric materials were obtained as follows :1. The effects of buffer layers on the crystallinity and superconductivity of BiSrCaCuO layer were studied to get high quality thin films. The buffer layers were found to reduce the strain caused by the lattice mismatch between the films and the substrates, and improve the superconducting transition temperature and the roughness of the film surface.2. The magnetic flux flow voltage excited by longitudinal ultrasound was measured for the above thin films and the bulk sintered samples. The experimental results were compared with theoretical ones based on the model of thermally assisted flux flow, and the problems to be solved were pointed out.3. The flux flow voltage was measured with a different vibrational mode of ultrasound which is related to the melting of the flux line lattice. A characteristic phenomenon was observed for the flux flow voltage.