Giant electric field–controlled magnetism in Bi _0.86 Sm _0.14 FeO ₃ multiferroic ceramics with Pna 2 ₁ symmetry

In the present work, Bi 0.86 Sm 0.14 FeO 3 ceramics with near Pna 2 1 single‐phase structure were obtained by a repeated longtime sintering process, and the dielectric, ferroelectric, and magnetic characteristics were determined together with the magnetoelectric coupling coefficient. The evolution of Pna 2 1 symmetry was revealed by transmission electron microscope analysis, and the ferroelectric transition from Pbnm to Pna 2 1 was determined by differential scanning calorimetry analysis together with the dielectric characterization, and the Curie temperature was determined as 195°C. The saturated polarization–electric field ( P–E ) hysteresis loop was obtained with P r = 12.2 μC cm −2 , and the unlocking of ferromagnetism was confirmed by the apparent magnetization–magnetic field ( M–H ) hysteresis loop with M r = 77.4 emu mol −1 . The giant electric field–controlled magnetism was due to the Pna 2 1 / R3c field–induced transition, which was confirmed by both structure analysis and theoretical calculation, and the change of remanent magnetization under an electric field was achieved up to 44.8 emu mol −1 (57.9%), which was much bigger than that of rare‐earth (RE)‐substituted BiFeO 3 ceramics without optimizing Pna 2 1 phase fraction. The present results might significantly deepen the physical understanding of Pna 2 1 phase and subsequently provide new hints on further enhancing electric field–controlled magnetism in RE‐substituted BiFeO 3 multiferroic ceramics.