Effect of interfacial strain on critical temperature of YBa2Cu3O7-δ thin films

Abstract

Ultrathin YBa2Cu3O7-δ (YBCO) films down to two unit cells thick have been prepared on LaAlO3 (LAO) and SrTiO3 (STO) substrates for the study of substrate-induced strain effects on critical transition temperature (Tc). The YBCO on LAO has a higher Tc than that on STO for very thin films, and this Tc difference increases with reduction of film thickness. X-ray diffraction experiments reveal that compressive strain exists in the a-b plane for YBCO thin films on LAO, while tensile strain occurs for films on STO. The different stresses in these films account for the Tc. difference. © 2000 American Institute of Physics.