Study of superconducting properties of ferrocene-added MgB2



In the present study, we have shown the effects of ferrocene (FeC10H10) addition on the superconducting properties of polycrystalline MgB2 superconductor using transport and magnetic measurements. The addition of FeC10H10 up to 2 wt% in the MgB2 sample has shown enhanced critical current density, JC in the entire magnetic field region without affecting much the transition temperature. At 10 K, with respect to a pristine MgB2 sample, JC has improved by a factor of 6.55 at 6 T applied field for 1 wt% FeC10H10. An improvement in the upper critical field, math formula and irreversibility field, Hirr has also been observed up to 2 wt% addition of FeC10H10. The value of math formula as obtained using the Ginzburg–Landau (GL)-theory fit of the experimental data increases by almost 2 T for 2 wt% FeC10H10-added MgB2 as compared to the pristine samples. From X-ray photoemission spectroscopy (XPS), we observed that the Fe is present in sample in the form of ferromagnetic oxides, Fe3O4 and γ-Fe2O3. These ferromagnetic inclusions provide efficient pinning centers to improve JC(H) behavior. The flux pinning mechanisms present in the FeC10H10-added samples are described and discussed in this paper.