Fabrication of superconducting MgB2 thin films on textured Cu(100) tape by hybrid physical-chemical vapor deposition
We report on the fabrication of superconducting MgB2 thin films on textured Cu(100) tape under low pressure and temperature by using a hybrid physical–chemical vapor deposition (HPCVD) technique to explore the possible broad range of deposition. Thermodynamic calculations for the Mg–B system have been carried out and the pressure–temperature phase diagram was obtained. Our results demonstrate that the deposition of superconducting MgB2 films is possible beyond the theoretically calculated growth window, where the sublimation of Mg is taking place. The structural and microstructural investigations reveal that MgB2 films are c-axis-oriented normal to the substrate. The highest Jc of ~1.34 × 105 A cm−2 at 5 K under 3 T is obtained for the film grown at 460 °C. The critical current density (Jc) and flux pinning force density (Fp) of MgB2 films are enhanced with decreasing growth temperature. This could be attributed to the high density of grain boundaries which may act as effective flux pinning centers. These findings suggest an alternative route to fabricate MgB2 tapes at low temperature for large scale applications.