Spacer-layer-tunable ferromagnetic half-metal-ferromagnetic insulator transition in SrVO<sub>3</sub>/SrTiO<sub>3</sub> superlattice

In this work, the first-principle calculations based on density functional theory (DFT) are employed to investigate the electronic and magnetic properties of SrVO₃/SrTiO₃(111) superlattices. The studies show that the transition from ferromagnetic half-metal to ferromagnetic insulator can be achieved by adjusting the thickness of the spacer-layer SrTiO₃. The interlayer coupling between the SrVO₃ sublayers can occur across two unit-cell (uc) distance of SrTiO₃, and the superlattice is ferromagnetic half-metal. When the SrTiO₃ sublayers are 3uc, a small band gap (about 0.28 eV) appears in the superlattice. When the SrTiO₃ sublayers are more than 3uc, the superlattice has a large band gap and exhibits ferromagnetic insulating state. Further studies show that the Ti-V mixed defects play an important role in realizing the transition of metal-insulator. Compared with the ideal interface, the Ti-V mixed interface can inhibit the interlayer coupling and induce the transition of ferromagnetic half-metal to ferromagnetic insulator. These results provide a theoretical basis for the transition of ferromagnetic half-metal to ferromagnetic insulator by adjusting the number of SrTiO₃ layers in SrVO₃/SrTiO₃(111) superlattices.