[17p-Z21-1~10] 11.3 Critical Current, Superconducting Power Applications

[17p-Z21-2] Critical review of “universal self-field critical current for thin-film SCs” by Tallon et al

〇Hirofumi Yamasaki¹ (1.ISS Organizing Committee)

Keywords:superconducting thin films, self-field critical current densities, nanoprecipitate pin

The author proposed that the self-field Jc of YBCO thin films is determined by the flux pinning with low-density of relatively-large nanoprecipitates. Then the Jc is expressed as Jc ~ Hc^2ξab ~ κφ0/λab^3 (1), where ξab is the GL coherence length and λab is the penetration depth. The equation (1) can explain the good correlation between 1/Jc(self) and surface resistance Rs, which is proportional to λab^3. Recently, Tallon et al proposed that the self-field Jc of type-II superconducting thin films is determined by a universal equation of Jc = Hc1/λ(T) = φ0/λ(T)^3 (2), and showed experimental results that obey the temperature dependence of Eg. (2) in many superconductors. However, Eq. (2) is questionable because it does not consider the pinning of flux lines entered from the edges of thin films. The author has considered that the Eq. (1) is the actual origin of temperature dependence of Eq. (2).