Magnesium Diboride Superconducting Films Synthesized by Different Electron-Beam Annealing Currents

Abstract

Considerable progress to synthesize magnesium diboride (MgB2) films by electron-beam annealing has been made. A series of MgB2 films with a Tc higher than 35 K had been fabricated. MgB2 film superconductivity is affected by electron-beam accelerating voltage, beam current, annealing duration, beam spot size and Mg/B ratio. In order to fabricate better MgB2 films, these influence factors must be intensively studied. In this paper, the influence of e-beam current on superconductivity was investigated with an accelerating voltage of 32 kV, an annealing time of 0.26 s and different annealing beam currents of 9.9 mA, 10.7 mA, 12.8 mA, 13.3 mA and 14.0 mA. The results show the MgB2 film with 12.8 mA has the highest Tc and the densest structure. Its zero-field Jc at 15K has reached 3.2×106 A/cm2. The variation of the film superconducting properties with the beam currents was grasped, which will lay the foundation for the fabrication of high quality MgB2 thin films