High-entropy enhanced room-temperature ferroelectricity in rare-earth orthoferrites

Single-phase multiferroic materials of rare-earth orthoferrites with magnetism and ferroelectricity are of great technological importance in storage devices. However, the polarization (P) of these materials is generally weak (0.01 μC·cm⁻²), and the ferroelectricity is reported to exist below room temperature (25 ℃). Here, (Bi_0.2La_0.2Y_0.2Dy_0.2Tb_0.2)FeO₃ (BLYDTFO) high-entropy oxides that exhibit a saturation P of 5.3 μC·cm⁻² at the electric field (E) of 45 kV·cm⁻¹ at room temperature was designed and fabricated by the conventional solid-phase method. The results show that configurational entropy introduces atomic disorder and a larger tilt of BO₆ octahedron, which facilitates non-centrosymmetric distortion and ferroelectricity at room temperature compared with other single components (LaFeO₃, YFeO₃, DyFeO₃, and TbFeO₃). This high-entropy approach expands the compositional window of the rare-earth orthoferrites to enhance the ferroelectricity in multiferroic applications.