Antiferrodistortive structural phase transition in compressively-strained epitaxial SrTiO₃ film grown on (La, Sr)(Al, Ta)O₃ substrate

(001)-epitaxial SrTiO₃ films were grown on (La, Sr)(Al, Ta)O₃ substrates for investigating the impact of biaxial strain on the antiferrodistortive (AFD) structural phase transition in SrTiO₃. The films were fully constrained by the substrates, which resulted in the large in-plane compressive strain of -0.9%. The AFD transition temperature estimated using temperature controlled x-ray diffraction and transmission electron microscope was over 150K higher than the theoretical prediction, but rather supported the experimental results reported on SrTiO₃ films on LaAlO₃ substrates.