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

Abstract

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.