Atomic-Scale Elucidation of Strain-Controlled Antiphase Boundary Architecture and Its Impact on Transport in LaNiO3 Thin Films

Epitaxial strain engineering provides an effective route for controlling defect configurations and physical properties in perovskite oxide thin films. In this study, LaNiO3 (LNO) films were epitaxially grown on LaAlO3 (LAO) and SrTiO3 (STO) substrates, where opposite in-plane strain types led to the formation of single-orientation horizontal and vertical antiphase boundaries. Atomic-scale analysis revealed that both types of boundaries exhibit an antiphase character with a half-unit-cell lattice displacement. Electrical transport measurements in the temperature range of 300−360 K showed that the LNO/STO film with vertical antiphase boundaries exhibited a higher in-plane resistivity and a lower Hall mobility than the film with horizontal antiphase boundaries. These results establish a clear correlation among the substrate strain type, antiphase boundary orientation, and in-plane electrical transport properties, providing a structural basis for defect engineering in correlated oxide films and for structural and transport regulation in nickelate-based systems.