Tailoring of magnetism & electron transport of manganate thin films by controlling the Mn–O–Mn bond angles via strain engineering

Abstract

AbstractStrain engineering beyond substrate limitation of colossal magnetoresistant thin (La0.6Pr0.4)0.7Ca0.3MnO3 (LPCMO) films on LaAlO3-buffered SrTiO3 (LAO/STO) substrates has been demonstrated using metalorganic aerosol deposition technique. By growing partially relaxed 7–27 nm thick heteroepitaxial LAO buffer layers on STO a perfect lattice matching to the LPCMO has been achieved. As a result, strain-free heteroepitaxial 10–20 nm thick LPCMO/LAO/STO films with bulk-like ferromagnetic metallic ground state were obtained. Without buffer the coherently strained thin LPCMO/STO and LPCMO/LAO films were insulating and weakly magnetic. The reason for the optimized magnetotransport in strain-free LPCMO films was found to be a large octahedral Mn–O–Mn bond angle φOOR ~ 166–168° as compared to the significantly smaller one of φOOR ~ 152–156° determined for the tensile (LPCMO/STO) and compressively (LPCMO/LAO) strained films.