Magnetoelectric Coupling Induced Orbital Reconstruction and Ferromagnetic Insulating State in PbZr_0.52Ti_0.48O₃/La_0.67Sr_0.33MnO₃ Heterostructures

Novel phenomena at the ferromagnetic/ferroelectric interface have generated much interest. Here, a ferromagnetic insulating state with the Curie temperature about 268–286 K in PbZr_0.52Ti_0.48O₃/La_0.67Sr_0.33MnO₃ heterostructures is induced and modulated by varying the PbZr_0.52Ti_0.48O₃ thickness. An abnormally enlarged c/a ratio in La_0.67Sr_0.33MnO₃ by strain-based coupling effect leads to d_3z²−r² orbital preferable occupancy. This orbital reconstruction modulates effective electron transfer and finally leads to a ferromagnetic insulating state. Valence change induced by charge-based coupling effect could be partially responsible for change in the Curie temperature in the strongly correlated electron system of La_1–xSr_xMnO₃. This work provides a deeper understanding of strain effects near the ferromagnetic/ferroelectric interface, especially in a PbZr_1–yTi_yO₃/La_1–xSr_xMnO₃ heterostructure system.