High field performance of nanodiamond doped MgB2 superconductor
The results from magnetotransport and magnetization of nanodiamond doped MgB2-nDx are reported. Superconducting transition temperature (Tc) is not affected significantly by x up to x=0.05 and latter decreases slightly for higher x>0.05. R(T) vs H measurements show higher Tc values under same applied magnetic fields for the nanodiamond added samples, resulting in higher estimated Hc2 values. From the magnetization measurements, it was found that irreversibility field value Hirr for the pristine sample is 7.5T at 4K and the same is increased to 13.5T for 3wt% nD added sample at the same temperature. The Jc(H) plots at all temperatures show that Jc value is lowest at all applied fields for pristine MgB2 and the sample doped with 3wt% nD gives the best Jc values at all fields. These results are discussed in terms of extrinsic pinning due to dispersed n-diamond in the host MgB2 matrix along with the intrinsic pinning due to possible substitution of C at boron site and increased interband scattering for highly ...