date:Univ Neuchatel, Inst Phys, CH-2000 Neuchatel, Switzerland; IBM Corp, Div Res, Zurich Res Lab, CH-8803 Ruschlikon, Switzerland; Univ Geneva, DPMC, CH-1211 Geneva, Switzerland
We have developed an approach to grow high quality ultra-thin films of La2-xSrxCuO4 with molecular beam epitaxy, by adding a homoepitaxial buffer layer in order to minimize the degradation of the film structure at the interface. The advantage of this method is to enable a further reduction of the minimal thickness of a superconducting La1.9Sr0.1CuO4 film. The main result of our work is that a single unit cell (only two copper oxide planes) grown on a SrLaAlO4 substrate exhibits a superconducting transition at 12.5 K (zero resistance) and an in-plane magnetic penetration depth lambda(ab)(0) = 535 nm. (C) 2003 Elsevier Ltd. All rights reserved.