Magnetic Anisotropy Controlled by Distinct Interfacial Lattice Distortions at the La_1–<i>x</i>Sr<i>_x</i>CoO₃/La_2/3Sr_1/3MnO₃ Interfaces

Abstract

Interface engineering is an important approach leading to multifunctional artificial materials. Although most of the previous works focused on the effects of the rotation/tilting of interfacial oxygen octahedron on perovskite multilayers, here, we report on a new kind of lattice distortion characterized by an off-center shift of the Mn ions within the MnO₆ oxygen octahedra at the interfaces of La_{1- x}Sr _xCoO₃/La_2/3Sr_1/3MnO₃/La_{1- x}Sr _xCoO₃/LaAlO₃ trilayers ( x = 0-1/3), which drives the initially perpendicularly aligned magnetic axis of the La_2/3Sr_1/3MnO₃ (LSMO) film toward the in-plane direction, though the film is in a strongly compressive state. It is further found that the magnetic anisotropy considerably depends on the content of Sr in La_{1- x}Sr _xCoO₃, enhancing as x decreases. The maximal anisotropy constant at 10 K is +2.5 × 10⁶ erg/cm³ for the trilayers with x = 0, whereas it is -1.5 × 10⁵ erg/cm³ for a bare LSMO film on LaAlO₃. On the basis of the analysis of X-ray absorption spectroscopy and the results of density functional theory calculations, we found that the off-center displacement of the Mn ions has caused a strong orbital reconstruction at interfaces, resulting in the anomalous spin orientation against magnetoelastic coupling.