Fabricating superconducting interfaces between artificially grown LaAlO₃ and SrTiO₃ thin films

Realization of a fully metallic two-dimensional electron gas (2DEG) at the interface between artificially grown LaAlO₃ and SrTiO₃ thin films has been an exciting challenge. Here we present for the first time the successful realization of a superconducting 2DEG at interfaces between artificially grown LaAlO₃ and SrTiO₃ thin films. Our results highlight the importance of two factors - the growth temperature and the SrTiO₃ termination. We use local friction force microscopy and transport measurements to determine that in normal growth conditions the absence of a robust metallic state at low temperature in the artificially grown LaAlO₃/SrTiO₃ interface is due to the nanoscale SrO segregation occurring on the SrTiO₃ film surface during the growth and the associated defects in the SrTiO₃ film. By adopting an extremely high SrTiO₃ growth temperature, we demonstrate a way to realize metallic, down to the lowest temperature, and superconducting 2DEG at interfaces between LaAlO₃ layers and artificially grown SrTiO ₃ thin films. This study paves the way to the realization of functional LaAlO₃/SrTiO₃ superlattices and/or artificial LaAlO₃/SrTiO₃ interfaces on other substrates. © 2014 Author(s).