PRESENTED ON-DEMAND ONLY: Tuning Multiferroic La_xSr_1-xFe₁₂O₁₉ from Ferroelectrics to Antiferroelectrics

The appearance of antiferroelectrics (AFE) in ferromagnetism (FM) system would give birth to a new type of multiferroic candidate, which is significant to the development of novel devices for energy storage. Here we demonstrate the realization of full antiferroelectrics in magnetic La_0.5Sr_0.5Fe₁₂O₁₉ system (AFE+FM), which also presents strong magnetodielectric response (MD) and giant magnetoresistance (GMR) effect. The combination of antiferroelectricity and ferromagnetism in one structure would create new types of multiferroic candidates. Here we propose a novel type of multiferroic candidate La_xSr_1-xFe₁₂O₁₉, whose room temperature state could be tuned from ferroelectrics to antiferroelectrics by changing <i>x</i> from 0 to 0.5. The antiferroelectric phase was achieved at room temperature by replacing 0.5 Sr²⁺ ions with 0.5 La²⁺ ions in SrFe₁₂O₁₉, whose phase transition temperature of ferroelectrics (FE) to antiferroelectrics was brought down from 174°C to -141°C, while the temperature of antiferroelectrics converting to paraelectrics (PE) shifts from 490°C to 234°C after the substitution, generating a wide space between -141°C~234°C to accommodate the antiferroelectric state in La_0.5Sr_0.5Fe₁₂O₁₉ system. The fully separated double P-E hysteresis loops reveal the antiferroelectrics in La_0.5Sr_0.5Fe₁₂O₁₉ ceramics. La_0.2Sr_0.7Fe₁₂O₁₉, however, exhibits a hybrid ferroelectric/antiferroelectric state. Both compounds exhibit strong ferrimagnetism. In addition, the La_0.5Sr_0.5Fe₁₂O₁₉ceramic demonstrates strong magnetoelectric coupling and giant magnetoresistance effect. A 1.1T magnetic field generates electronic polarization of 0.95mC/cm², reduces the resistance by 117% (GMR), enhances dielectric constants by 540% and right shifts the maximum dielectric loss peak by 208 kHz, showing giant magnetodielectric effect (GMD). The combined functional responses provide an opportunity to develop novel multiferroic memories and energy storage devices.