Perpendicular magnetic anisotropy induced by La2/3Sr1/3MnO3–YBaCo2O5+δ interlayer coupling

Abstract

The heterostructure with symmetry-mismatched interface provides a promising playground for the exploration of emergent phenomena. Herein we reported a systematic investigation on La_2/3Sr_1/3MnO₃/YBaCo₂O_5+δ (LSMO/YBCO) grown on SrTiO₃, a heterostructure formed by perovskite oxides of different symmetry. High-resolution lattice image shows the formation of high quality perovskite LSMO and A-site cation-ordered oxygen-deficient double perovskite YBaCo₂O_5+δ, without any signatures of atomic reconfiguration at interface. Surprisingly, the YBCO-buffered LSMO exhibits perpendicular magnetic anisotropy (PMA), though bare LSMO film is in-plane anisotropic. The PMA is robust, appearing even when the thickness of YBCO is only one unit cell. The typical anisotropy constant is ~4×10⁶ erg/cm³. X-ray absorption spectroscopy analysis reveals a preferential occupation of the d_3z²-r² orbital compared with d_x²-y², which is confirmed by density functional theory calculations. This orbital reconstruction accounts for the PMA. The formation of covalent bond between Mn and Co caged by different oxygen polyhedrons, octahedron and square pyramid, respectively, stabilizes the orbital reconstruction, resulting in the anomalous spin orientation.