A simple method for the enhancement ofJc inMgB2 thick films with an amorphous SiC impurity layer

Abstract

We investigated the effect of SiC doping on the critical current density (Jc)in MgB2 thick films using amorphous SiC impurity layers of various thicknesses:7, 14, 35, and 70 nm. SiC impurity layers were first deposited on theAl2O3(0001) substrates at room temperature by using a pulsed laser deposition system, after whichMgB2 films were grown on the SiC deposited precursor substrates by using a hybridphysical–chemical vapor deposition technique at a low growth temperature of480 °C. All samples showed a high transition temperature of∼40 K irrespective of the thickness of the impurity layer. The grain sizes of theMgB2 films slightly increased from 400 to 488 nm with increasing thickness of the impurity layer. TheMgB2 thick film with a 35 nm thick SiC impurity layer exhibited the highestJc, while all SiC doped samples showed a higherJc than apure MgB2 thick film throughout the whole magnetic field region. These resultssuggest that the SiC particles of the impurity layer diffused into theMgB2 films during film growth, and the SiC particles, along with the columnar grain boundaries in theMgB2 thick films, act as strong pinning centers.