MgB2 thin film fabrication with excess Mg by sequential e-beam evaporation and transport properties under magnetic fields

• The first excess mgB2 fabrication using e-beam technique.
• Fabrication of MgB2 using e-beam with low annealing temperatures.
• The improvements of critical current density and transport properties.

Superconducting MgB2 thin films with different thicknesses were fabricated by excess Mg using sequential electron beam evaporation technique. The flux rate of Mg and B were chosen as 3 nm/sn and 0.5 nm/sn respectively. The thickness of Mg/B layer was determined as 3/1 which causes an excess Mg for MgB2 formation. After two-step preparation process, the superconducting transition temperatures were found in the range of 32–37 K with a sharp transition to zero resistance state. The irreversibility fields, upper critical fields and activation energies were derived from magneto resistivity curves. The transport critical current densities of films were determined from I–V characteristics under different applied fields and the data was extrapolated for determination of value of the 0 K.