Room temperature polar and weak-ferromagnetic oxide with low dielectric loss

Abstract

Single-phase materials that are simultaneously ferroelectric and ferromagnetic at room temperature are promising for devices such as non-volatile random-access memory. Perovskite BiFeO3 which crystallizes in the polar rhombohedral structure (R3c) is ferroelectric and antiferromagnetic at room temperature. Here, we report a family of perovskite oxides in the BiFeO3 – Bi2/3TiO3 – ATiO3 (where A2+ is divalent alkaline earth metal ions e.g., Ca2+, Sr2+, Ba2+) ternary phase diagram that is polar as well as weak ferromagnetic above room temperature. The composition (Bi0.9167A0.075)(Fe0.9Ti0.1)O3 crystallizes in the polar rhombohedral structure space group R3c as corroborated by powder X-ray and neutron diffraction analysis. The nearly pure A-site perovskite possesses a long-range magnetic ordering above room temperature. These perovskites show a low dielectric loss, and the electrical response is dominated by grain contributions below 723 K.