Control of Oxygen Deficiency in Superconducting Y₁Ba₂Cu₃O_7-yFilms Using a Solid-State Electrolyte

Y₁Ba₂Cu₃O_7-y(YBCO) films deposited on YSZ are coated with MgO films in order to isolate the YBCO film from the atmosphere. An electrochemical technique using a solid-state electrolyte is applied to this airtight structure to control the density of the oxygen deficiency y in the YBCO film. The resistivity of the YBCO film at 500°C is found to be reversibly changed by the applied current. The change of y by the applied current is confirmed by the change of the lattice parameter c. From the temperature dependence of the resistivity of the film, it is shown that T_ccould be controlled and fixed by using this technique.