Fabrication of High-Temperature Quasi-Two-Dimensional Superconductors at the Interface of a Ferroelectric Ba_{0.8}Sr_{0.2}TiO_{3} Film and an Insulating Parent Compound of La_{2}CuO_{4}.

We report the first observation of superconductivity in a heterostructure consisting of an insulating ferroelectric film (Ba_{0.8}Sr_{0.2}TiO_{3}) grown on an insulating parent compound of La_{2}CuO_{4} with [001] orientation. The heterostructure was prepared by magnetron sputtering on a nonatomically flat surface with inhomogeneities of the order of 1-2 nm. The measured superconducting transition temperature T_{c} is about 30 K. We have shown that superconductivity is confined near the interface region. Application of a weak magnetic field perpendicular to the interface leads to the appearance of the finite resistance. That confirms the quasi-two-dimensional nature of the superconductive state. The proposed concept promises ferroelectrically controlled interface superconductivity which offers the possibility of novel design of electronic devices.