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

这项工程被计划为两年计划。然而，由于激光烧蚀设备的制作从最初的计划推迟了，多层薄膜的制备没有成功。在制备BiSrCaCuO薄膜的同时，用直流溅射方法制备了BiSrCaCuO薄膜，并测量了超声激励下的磁通电流电压。1.为了获得高质量的BiSrCaCuO薄膜，研究了缓冲层对BiSrCaCuO薄膜结晶度和超导电性的影响。结果表明：1.缓冲层的加入降低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。测量了上述薄膜和块体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结果进行了比较，并指出了需要解决的问题。用不同的超声振动模式测量了与磁通线阵融化有关的磁通流量电压。观察到了磁通流动电压的特征现象。

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.