Symmetry mismatch-driven perpendicular magnetic anisotropy for La_2/3Sr_1/3MnO₃/LaCoO_2.5 (LSMO/LCO) heterostructures

Grouping different transition metal oxides (TMOs) together by interface engineering is an important route towards emergent phenomenon. While most of the previous works focused on the interface effects on perovskite/perovskite (P/P) heterostructures, herein we report on a fabrication of perovskite/brownmillerite (P/B)type La_2/3Sr_1/3MnO₃/LaCoO_2.5 (LSMO/LCO) heterostructure on (001)-orientened SrTiO3 substrates.Through the magnetic measurements, we find the perpendicular magnetic anisotropy (PMA) of the LSMO layer, which keeps in-plane easy axis under tensile strian.As evidenced by high resolution lattice structure analysis and density functional theory calculations, alternatively stacking of perovskite La_2/3Sr_1/3MnO₃ and brownmillerite LaCoO_2.5 results in a distinct relaxation of the neighboring MnO₆ and CoO₄ polyhedra that is not seen at the P/P interface,causing distinct orbital reconstructions thus the PMA. Moreover, the PMA is robust, with an anisotropy constant two orders of magnitude greater than that the in-plane anisotropy of the P/P interface.The present work demonstrates the great potential of symmetry engineering in designing artificial materials on demand.