Increase in the infield critical current density of MgB2 thin films by high-temperature post-annealing

Hiroto Kambe,Ataru Ichinose,Toshiaki Kusunoki,Iwao Kawayama,Takumu Iwanaka,Naoya Kitamura,Toshiya Doi

doi:10.35848/1882-0786/abdac3

Abstract

We propose a novel fabrication technique based on the formation of a Nb protective layer on a MgB2 thin film and high-temperature post-annealing to increase the critical current density (J c) of MgB2 films under an external magnetic field. Analyses of the crystal structure and the composition of the processed MgB2 films confirmed the suppression of the evaporation and oxidation of Mg by high-temperature annealing above 550 °C. The MgB2 film annealed at 650 °C exhibited a J c of 1.62 MA cm−2 under 5 T, which is the highest reported value for MgB2 films, wires, and bulk samples to date.

Highlights

We propose a novel fabrication technique based on the formation of a Nb protective layer on a MgB2 thin film and high-temperature post-annealing to increase the critical current density (Jc) of MgB2 films under an external magnetic field
In one of our previous studies, we demonstrated the effects of in situ annealing under ultrahigh vacuum (
700 °C.13) The results showed that the Nb protective layer facilitated the post-annealing of MgB2 thin films at 650 °C

Summary

Introduction

Increase in the infield critical current density of MgB2 thin films by high-temperature post-annealing Hiroto; Kawayama, Iwao; Kitamura, Naoya; Ichinose, Ataru; Iwanaka, Takumu; Kusunoki, Toshiaki; Doi, Toshiya Hiroto Kambe1, Iwao Kawayama1, Naoya Kitamura1, Ataru Ichinose2, Takumu Iwanaka3, Toshiaki Kusunoki3, and Graduate School of Energy Science, Kyoto University, Kyoto 606-8501, Japan

Results

Conclusion