Magnetoelectric properties of MgB2 superconductor by SiC doping

Effect of SiC, as carbon source doping, by diffusion method on the lattice parameter, critical temperature (T_c) and critical current density (J_c) has been studied. The broadening of full width at half maximum (FWHM) values in XRD patterns with increasing of the doping level indicates smaller grains and imperfect MgB₂ crystallinity, whereas the carbon substitution into the boron site was confirmed by the shrinkage of the lattice parameter a. Despite of lower T_c´s, J_cs of the doped samples are higher than the undoped sample over 4 T at 20 K and over 7 T at 5 K, respectively. MgB₂ with the 10 % of SiC doping showed the highest J_c with the value of 10⁵ A/cm² at 5 K and 4 T while the 2.5% SiC doped sample showed 7 factor of J_c enhancement compared to pristine sample at 20 K and 4.5 T. J_c enhancement by different doping level at respective temperature suggests, impurities such as Mg₂Si, MgB₂C₂ and MgO play a significant role in 20 K while carbon substitution effect dominances the flux pinning in 5 K. Our results also demonstrate that flux pinning and the J_c can be tailored for various applications depending on the operating temperature and external magnetic field.