Critical current density of MgB2 thin films and the effect of interface pinning

Abstract

Preferentially oriented MgB2 thin films with c-axis normal to the surface have been prepared and characterized for microstructure andtransport properties. The magnetic field dependence of superconducting critical current densityJc has been determined from the magnetization hysteresis(M–H) loops at various temperatures using the Bean’s critical state model. HighJc ofthese films show their potential for applications. We have also measured the angular dependences ofJc. The angular dependence is seen to be in agreement with theanisotropic Ginzburg–Landau model except that at angles close to theab plane, increased pinning due to film–substrate interaction is observed. The angularrange where interface pinning is effective has been determined by measurement ofasymmetry in dissipation on reversal of current for fields applied at angles close to theab plane.