Growth of 200 Å superconducting Bi-Sr-Ca-Cu oxide thin films

Preferentially ĉ-axis oriented superconducting Bi-Sr-Ca-Cu oxide films as thin as 200 Å have been successfully grown on MgO(100) substrates. Even though such thin films are only 6–7 unit cells thick, they still exhibit bulk superconducting properties. These films typically exhibit a superconducting transition temperature at 80 K and a critical current density of 105 A/cm2 at 50 K as determined by transport measurements. The ability to grow even thinner films is controlled by the exact film stoichiometry and the smoothness of the substrate surface.