Superconducting Transition in Electron-Doped 12CaO·7Al₂O₃

Abstract

It was reported that a mixed light metal oxide compound, 12CaO·7Al₂O₃ (C12A7), which is known as a constituent of aluminous cement, became a superconductor at an ambient pressure by the exclusive replacement of extra-framework oxygen ions in subnanometer-sized crystallographic cages with electrons. Temperature dependences of resistivity, magnetic susceptibility, and magnetic field dependent resistivity of single-crystals and thin films revealed superconducting transition at temperature (T_c) of ∼0.4 K and a critical magnetic field of ∼30 mT. T_c varies 0.2–0.4 K with the electron concentration. The interaction of the anionic electrons in the free space (cages) with the cationic framework may be responsible for the emergence of the superconducting state.