Ultrasonic studies of thermally assisted flux flow and intrinsic pinning in high-Tc phase Bi-Pb-Sr-Ca-Cu-O ceramics

✍ Scribed by Yuuji Horie; Takayoshi Miyazaki; Takeshi Fukami; Ahmed A.A. Youssef

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 790 KB
• Volume: 176
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(91)90059-8

✦ Synopsis

The temperature dependence of the ultrasonic attenuation coefficient a (T, H) and sound velocity Vs (T, H) were measured under magnetic fields for high-To phase Bi-Pb-Sr-Ca-Cu-O ceramic samples aligned with the c-axis. In the case H.I_ k, where k is the direction of sound propagation, a broad peak was observed in the a ( T, 10T)-a ( T, 0 T) versus T curve at T~ 65 K accompanied with a broad step in the Vs(T, 10 T)-Vs(T, 0 T) versus T curve. On the other hand, the peak and the step were also observed in the case of HIIk, were the temperature position shifted down to T~ 50 K, and the width was narrower than in Hi k. The behavior was explained in terms of thermally assisted flux flow in which flux lines are pinned by intrinsic pinning centers.