Spontaneous polarization, n-type half-metallicity, low lattice thermal conductivity, and high structure stabilities in F@O-doped PbTiO ₃

Materials displaying ferroelectric and ferromagnetic properties offer a fascinating foundation for future spintronic innovations like multi-state random-access memory and data storage devices. Herein, numerous features of pristine and F@O-doped-PbO (PO)/TiO₂ (TO)-layer PbTiO₃ perovskite oxides are investigated <i>via ab initio</i> calculations. The calculated negative formation enthalpies and elastic coefficients verify the thermodynamic and mechanical stability of the structures, respectively. The pristine motif exhibits a giant spontaneous polarization (<i>P</i>) of 88 μC cm^-2, having a non-magnetic insulating state with an indirect energy gap (<i>E</i> _g) of 2.11 eV. It appears that the dopant reduces the structural distortions, lowering <i>P</i> to 42.56/42.78 μC cm^-2 in the F@O-doped PO/TO-layer-based structure. The most notable aspect of the present study is that F-doping in the PO layer induces an n-type half-metallic (HM) ferromagnetic (FM) behavior with a total magnetic moment (<i>m</i> _t) of 1.0 <i>μ</i> _B. It is found that Ti ions are the main contributor to the magnetism, which is confirmed by spin-magnetization density isosurface plots. Additionally, a large <i>E</i> _g of 2.49 eV in the spin-minority channel is found, which is large enough to ensure the HM state and avoid reverse leakage current. Conversely, the F@O-doped TO-layer-based system transforms to an FM semiconductor with an <i>E</i> _g of 0.23 eV. Interestingly, the highest figure of merit of 0.72/0.56/0.49 is predicted at 700/700/400 K for the pristine/F@O-doped PO/TO-layer-based structures with the inclusion of lattice thermal conductivity. Thus, due to high structural stability, high <i>P</i>, half-metallicity, and low thermal conductivity, the F@O motif emerges as a promising candidate for various potential applications in spintronics and energy conversion.