Modifying the crystal structure and corresponding functional properties of complex oxides by regulating their oxygen content has promising applications in energy conversion and chemical looping, where controlling oxygen migration plays an important role. Therefore, finding an efficacious and feasible method to facilitate oxygen migration has become a critical requirement for practical applications. Here, we report a compressive-strain-facilitated oxygen migration with reversible topotactic phase transformation (RTPT) in La0.5Sr0.5CoO x films based on all-solid-state electrolyte gating modulation. With the lattice strain changing from tensile to compressive strain, significant reductions in modulation duration (∼72%) and threshold voltage (∼70%) for the RTPT were observed, indicating great promotion of RTPT by compressive strain. Density functional theory calculations verify that such compressive-strain-facilitated efficient RTPT comes from significant reduction of the oxygen migration barrier in compressive-strained films. Further, ac-STEM, EELS, and sXAS investigations reveal that varying strain from tensile to compressive enhances the Co 3d band filling, thereby suppressing the Co–O hybrid bond in oxygen vacancy channels, elucidating the micro-origin of such compressive-strain-facilitated oxygen migration. Our work suggests that controlling electronic orbital occupation of Co ions in oxygen vacancy channels may help facilitate oxygen migration, providing valuable insights and practical guidance for achieving highly efficient oxygen-migration-related chemical looping and energy conversion with complex oxides.

Tailoring the interface between organic semiconductor (OSC) and ferromagnetic (FM) electrodes, that is, the spinterface, offers a promising way to manipulate and optimize the magnetoresistance (MR) ratio of the organic spin valve (OSV) devices. However, the non‐destructive in situ regulation method of spinterface is seldom reported, limiting its theoretical research and further application in organic spintronics. (La2/3Pr1/3)5/8Ca3/8MnO3 (LPCMO), a recently developed FM material, exhibits a strong electronic phase separation (EPS) property, and can be employed as an effective in situ spinterface adjuster. Herein, we fabricated a LPCMO‐based polymer spin valve with a vertical configuration of LPCMO/poly(3‐hexylthiophene‐2,5‐diyl) (P3HT)/Co, and emphasized the important role of LPCMO/P3HT spinterface in MR regulation. A unique competitive spin‐scattering mechanism generated by the EPS characteristics of LPCMO inside the polymer spin valve was discovered by abstracting the anomalous non‐monotonic MR value as a function of pre‐set magnetic field (Bpre) and temperature (T). Particularly, a record‐high MR ratio of 93% was achieved in polymer spin valves under optimal conditions. These findings highlight the importance of interdisciplinary research between organic spintronics and EPS oxides and offer a novel scenario for multi‐level storage via spinterface manipulation.