酸化物超電導体の高Jc化

抄録

One of the most important properties for application of superconductors is critical current density(Jc). Jc of order 10⁵ to 10⁶A/cm² is required often in the presence of large magnetic fields. However, Jc values of oxide superconductors remained low except thin films. It is also pointed out that large dissipation or flux creep becomes a serious problem for applications at higher temperatures. In fact, large flux creep is observed in thin films despite high Jc.
In order to achieve high Jc values, we need to introduce effective pinning centers which can prevent the motion of flux against the Lorentz force (FL=JxB). In this paper, I first summarize how Jc is determined in type II superconductors. Then I present the methods to increase Jc values in oxide superconductors and show that the flux creep rate becomes small when the pinning force or Jc is increased. Finally I propose some possible applications for high Jc bulk oxide superconductors.