We review several novel classes of new superconductors discovered within the last 10 years: 1) graphite intercalated llerene superconductors, 3) diamond and wide-gap superconductors, 4) aromatic superconductors, 5) MgB2 superconductors, 6) layered nitride superconductors and 7) iron-based superconductors. Finally, we briefly comment perspective on higher-Tc superconductors.
There has been a great deal of activity recently focused on REBa2Cu3Oy (REBCO) films with BaSnO3 (BSO) nanorods. It is known that BSO nanorods exert a strong pinning force on the flux line along the c-axis of REBCO. Previously, we fabricated non-stoichiometric Sm1.04Ba1.96Cu3Oy films with BSO nanorods. However, the superconducting properties and flux pinning properties of these films were inferior to those of BSO-doped YBCO films reported in the literature. In this study, we investigate the effect of the difference in Sm1+xBa2-xCu3Oy (SmBCO) composition ratio on the flux pinning force of BSO nanorods. We fabricated BSO-doped Sm1Ba2Cu3Oy film [SmBCO (x=0)] and BSO-doped Sm1.04Ba1.96Cu3Oy film [SmBCO (x=0.04)]. From TEM observations, the BSO nanorods in SmBCO (x=0) had grown parallel to the c-axis of SmBCO. In SmBCO (x=0.04), however, the BSO nanorods were angled. We measured the magnetic field dependence of Jc and then estimated Fp from Jc-B curves at 77 K in B//c. The FpMAX value of SmBCO (x=0) and SmBCO (x=0.04) reached 24.5 and 14.8 GN/m3, respectively. Thus, the pinning force of BSO nanorods in SmBCO (x=0) was stronger than that of SmBCO (x=0.04). These results indicate that the composition ratio of SmBCO affects the growth of BSO nanorods in BSO-doped SmBCO films, and that the shape of BSO nanorods has an influence on the superconducting properties of SmBCO film in a magnetic field.