Hexagonal Phase Stabilization and Multiferroicity in (Tm,Yb,Lu,In,Sc)FeO3 High-Entropy Ceramics

Abstract Geometric ferroelectrics hexagonal RFeO3 (h-RFeO3) has emerged as a prominent class of single-phase multiferroic materials, exhibiting magnetoelectric coupling by the spin–lattice coupling mechanism. However, stabilizing the hexagonal structure for RFeO3 remain challenging. Herein, we report the synthesis of stabilizing the pure hexagonal structure of (Tm,Yb,Lu,In,Sc)FeO3 high-entropy ceramics through the incorporation of (Tm,Yb,Lu,In,Sc) at the R-site via solid-state sintering without precursors. The samples retained polar hexagonal structure up to a ferroelectric transition temperature above 1373 K. The samples exhibit complex magnetic anomalies, including antiferromagnetic transition (TN ∼ 232 K) and spin reorientation behavior (TSR ∼ 156 K) based on comparison with established h-RFeO3 systems. Furthermore, significant coupling between magnetic and dielectric degrees of freedom or magnetoelectric coupling effect was observed, as evidenced by a dielectric anomaly near the spin reorientation temperature. Remarkably, periodic modulation of polarization by applied periodic magnetic fields was achieved at 2 K. The findings highlight the potential of the high-entropy strategy for designing novel multiferroic materials and provide new insights into magnetoelectric coupling in high-entropy systems.