Step Terrace Tuned Anisotropic Transport Properties of Highly Epitaxial LaBaCo₂O_5.5+δ Thin Films on Vicinal SrTiO₃ Substrates

Highly epitaxial LaBaCo₂O_5.5+δ (LBCO) thin films were grown on different miscut (001) SrTiO₃ substrates (miscut angle of 0.5°, 3.0°, and 5.0°) to study the substrate surface step terrace effect on the in-plane electrical transport properties. The microstructure studies by X-ray diffraction and transmission electron microscopy indicate that the as-grown films are A-site disordered cubic perovskite structures with the c-axis highly oriented along the film growth direction. The four-probe scanning tunneling microscopy (STM) studies show that the LBCO thin films grown on the vicinal SrTiO₃ substrates have a typical semiconductor behavior with the substrate surface terrace step inducing anisotropic electronic transport properties. These results indicate that in highly epitaxial thin films the surface terrace step induced local strains can play an important role in controlling the electronic transport properties and the anisotropic nature.