Tuning of the in-plane strain in cuprate thin films using a solid-solution compound as a buffer layer

摘要

In order to tune the epitaxial strain between a superconducting cuprate thin film and a substrate, we introduce a buffer layer of LaSrAl_(1-z)Ga_zO_4 which forms solid solutions for the entire range from z = 0-1. Thin films of La_(1.875)Ba_(0.125)CuO_4/LaSrAl_(1-z)Ga_zO_4 grown by pulsed laser deposition have been characterized by x-ray diffraction and resistivity measurements. The c-axis length of La_(1.875)Ba_(0.125)CUO_4 on the buffer layer reveals a systematic change with z indicating that the epitaxial strain is reasonably controlled. The films within the composition range of z = 0.2-0.6 show superconductivity with systematic change of the critical temperature, while the sample with z = 0.8 is insulating below 100 K.