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

概要

We propose a novel fabrication technique based on the formation of a Nb protective layer on a MgB₂ hin film and high-temperature post-annealing to increase the critical current density (Jc) 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 Jc of 1.62 MA cm⁻² under 5 T, which is the highest reported value for MgB₂ films, wires, and bulk samples to date.

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