Comparison of flux pinning in superconducting TlCaBaCuO crystals and thin films

✍ Scribed by Masao Nakao; Kenichi Kawaguchi; Hiroaki Furukawa; Kazuaki Shikichi; Yuh Matsuta

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 121 KB
• Volume: 162-164
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(89)91205-7

✦ Synopsis

We report direct observation of the flux pinning behavior of a TltCa2Ba2Cu30, highly oriented thin film, a randomly oriented polycrystalline thin film and a Tl~CaBa,eu20, single crystal. From the temperature dependence of the critical current densities Jc at zero field, activation energies Uo are estimated to be 110, 110 and 40 meV, respectively. Strong time-logarithmic magnetic relaxation M(t,T) was observed both in single crystals and in thin films. Within a thermally activated flux motion (TAFM) model, the distribution of activation energies p (Uo) is determined from data on the time and temperature dependence of bl(t,T) for the highly oriented film. The presence of a high-energy tail in the distribution suggests that the TAFM model can not be described by a single activation energy Uo; the effective Uo value increases rapidly with temperature.