Pinning force of twin planes or grain boundaries in high Tc superconductors

✍ Scribed by P.H. Kes; A. Pruymboom; J.van den Berg; J.A. Mydosh

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 448 KB
• Volume: 29
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(89)90165-3

✦ Synopsis

The elementary interaction of a grain boundary or twin plane is computed using Thuneberg's formulation in the Ginzburg-Landau regime and simply extending this to low temperatures.

The computation is carried out both for isolated flux lines and close to Be2 for strongly overlapping vortices. The volume pinning force is subsequently derived for three relevant situations: isolated vortices with flux line spacing either much smaller or larger than the twin plane spacing, and for overlapping flux lines. The resulting Fp(B) curve has a dome-shaped character. The reduced field at which it attains its maximum value is a function of temperature.

At 70 K it lies at B/Bc2~0.5. The low field and low temperature prediction is in good agreement with the experimental data. Predictions for the potential values of Fp and Jc at 77 K are given. These are much larger than the experimental results. We believe this discrepancy is caused by thermally assisted flux motion.