Anomalous magnetism in strained La_1-xSr_xCoO ₃epitaxial films (0≤x≤0.5)

Spin state controlling has always been a focus of intensive studies due to its importance for novel effect exploration and information technology. Complex oxides with competitive mechanisms are suitable objects of study for this purpose due to their susceptibility to external stimuli. Perovskite cobaltate La_1-xSr_xCoO₃ is one of such oxides. Combined effects of lattice strains and hole-doping have been studied for the LSCO films with 0≤x ≤0.5. It is found that the lattice strain, either tensile or compressive, destabilizes the ferromagnetic (FM) state of the epitaxial films, leading to a nonmagnetic state that extensively exists in a doping window embedding deep into the range of the FM phase in bulk counterparts. Density functional theory calculations reveal a distinct spin state transition due to the combined effects of lattice distortion and hole-doping, explaining the unique magnetic behaviors of LSCO.