Unprecedented High Irreversibility Line in Nontoxic Cuprate Superconductor (Cu,C)Ba2Ca3Cu4O11+delta

Abstract: One of the key factors limiting the high power applications for a type-II superconductor is the irreversibility line Hirr(T) which reflects the very boundary of resistive dissipation in the phase diagram of magnetic field versus temperature. In cuprate family, the Y-, Bi-, Hg- and Tl-based systems have superconducting transition temperatures exceeding the liquid nitrogen boiling temperature (~77K). However, the toxic elements Hg and Tl in the latter two systems strongly constrain the possible applications. The Bi-based (2223) system is nontoxic, but the irreversibility magnetic field is strongly suppressed in the liquid nitrogen temperature region. For this purpose, the best perspective so far is relying on the YBa2Cu3O7 (Tc~90 K) system which is nontoxic and has a relatively high irreversibility magnetic field. Here we report the study of a nontoxic superconductor (Cu,C)Ba2Ca3Cu4O11+{\delta} with Tc = 116K. It is found that the irreversibility magnetic field is unprecedentedly high among all superconductors and it thus provides a great potential of applications in the liquid nitrogen temperature region.