Emergence of half-metallic ferromagnetism in transition metal substituted Na0.5Bi0.5TiO3

Multifunctional materials with prominent properties such as electrical, ferroelectric, magnetic, optical, and magnetooptical are of keen interest to several practical implications. In the roadmap of designing such materials, in the present work, using density functional theory based first-principles calculations, we have investigated the properties of transition metals (TM)-substituted ${\mathrm{Na}}_{0.5}{\mathrm{Bi}}_{0.5}{\mathrm{TiO}}_{3}$ (NBT). Our calculations predict the emergence of half-metallic ferromagnetism in (TM)-substituted NBT. Nonzero magnetic moments of 1.5 and 1.9 ${\ensuremath{\mu}}_{\mathrm{B}}/\mathrm{f}.\mathrm{u}.$, respectively, are obtained for 25% Ni and Fe. Our data on optical properties for pure NBT are in excellent agreement with the available theory and experiments. For Ni/Fe-NBT, we observed a diverging nature of static dielectric constant, which could be attributed to the induced metallic character in the system. Our simulations on MOKE predict significant Kerr signals in both Ni and Fe-substituted NBT, which suggests transition metal substituted NBT as potential candidate for magnetooptic applications.