Proximity-Induced Interfacial Antiferromagnetic Coupling in EuO/KTaO₃ Heterostructures with LaTiO₃ Buffer Layers

Artificial oxide heterostructures provide valuable opportunities for tailoring interfacial magnetic coupling, which is a central topic of spintronics. In this work, the antiferromagnetic interfacial magnetic coupling is demonstrated in EuO/KTaO₃ (001) heterostructures by introducing a LaTiO₃ (LTO) buffer layer. Depth-resolved polarized neutron reflectometry reveals that ferromagnetic EuO induces magnetism in the adjacent LTO buffer layer and the interfacial KTaO₃ (KTO) through the magnetic proximity effect (MPE). Remarkably, the introduction of the LTO buffer layer at the EuO/KTO interface results in antiparallel alignment between the interfacial KTO layer and EuO, indicating proximity-induced antiferromagnetic coupling across the spacer layer. Anomalous Hall effect and hysteretic magnetoresistance measurements indicate the presence of spin-polarized 2D electron gases in the interfacial layer of KTO. The maximum thickness of the LTO buffer layer for EuO to be able to magnetize KTO is 8 uc (≈3.2 nm), beyond which no hysteretic magnetoresistance is observed. Density functional theory calculations suggest that antiferromagnetic coupling lowers the system energy in LTO-buffered EuO/KTO heterostructure, corroborating the experimental findings. This work highlights the crucial role of interface engineering in controlling interfacial magnetic coupling, providing novel pathways for designing advanced spintronic devices.