Anomalous ferromagnetism and magneto-optic Kerr effect in rare-earth substituted Na_0.5Bi_0.5TiO₃ Available to Purchase

Designing multifunctional materials with prominent electrical, optical, and magnetic properties is of keen interest to many technological applications. In the roadmap for designing such materials, we have investigated the rare-earth (Nd and Er)-substituted NBT using first-principles calculations. Our calculation predicts the emergence of magnetic degrees of freedom in these materials. The magnetic moments obtained, for the largest concentration of $25%$⁠, are $≈1.47$ and 1.49  $μ B/f.u.$⁠, respectively, for Nd-NBT and Er-NBT. The mechanism for nonzero magnetic moments in (Nd/Er)-NBT is traced to the presence of unpaired $f$-electrons in the systems. Our simulations on magneto-optic effects show a significant Kerr signal of 0.7  $°$ in both the materials. This suggests rare-earth substituted NBT as potential candidates for magneto-optical applications and motivates more theoretical and experimental works along this direction.