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

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 similar to 1:47 and 1.49 mu(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 magnetooptic effects show a significant Kerr signal of 0.7 degrees 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. Published under an exclusive license by AIP Publishing.