[17a-Z21-1~6] 11.2 Thin and thick superconducting films, coated conductors and film crystal growth

[17a-Z21-6] Superconducting properties and microstructures of post-annealed MgB₂ thin film with Ni protection layer

〇Toshiya Doi¹, Hiroto Kambe¹, Iwao Kawayama¹, Takumu Iwanaka^1,2, Toshiaki Kusunoki², Ataru Ichinose³ (1.Kyoto Univ., 2.Hitachi Ltd., 3.CRIEPI)

Keywords:superconductor, MgB2 thin film, post-annealing

As-grown MgB₂ thin films with high Jc were post-annealed for further improvement of J_c. Ni was chosen as the protection layer for Mg evaporation during the post-annealing. The T_c of the as-grown sample was 34.4 K, but it increased by about 0.8 K to 35.2 and 35.0 K by post-annealing at 450 and 550 °C × 1 h. However, the higher annealing temperature of 650 °C decreased the T_c <10 K.