Preferentially oriented MgB2 thin films with the c-axis normal to the surface were prepared and characterized for microstructure and transport properties. The magnetic field dependence of superconducting critical current density JC was determined from the magnetization hysteresis (M–H) loops at various temperatures using the Bean’s critical state model. High JC of these films showed their potential for applications. Measurements were also made of the angular dependences of JC. The angular dependence was seen to be in agreement with the anisotropic Ginzburg–Landau model except that at angles close to the ab plane, increased pinning due to film–substrate interaction was observed. The angular range where interface pinning was effective was determined by measurement of asymmetry in dissipation on reversal of current for fields applied at angles close to the ab plane.

Critical Current Density of MgB2 Thin Films and the Effect of Interface Pinning. E.M.Choi, S.K.Gupta, S.Sen, H.S.Lee, H.J.Kim, S.I.Lee: Superconductor Science and Technology, 2004, 17, S524-7