Antiferroelectrics and Magnetoresistance in La0.5Sr0.5Fe12O19 Multiferroic System

Abstract

The appearance of antiferroelectrics (AFE) in the ferrimagnetism (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 a magnetic La0.5Sr0.5Fe12O19 system (AFE+FM), which also presents a strong magnetodielectric response (MD) and magnetoresistance (MR) effect. The antiferroelectric phase was achieved at room temperature by replacing 0.5 Sr2+ ions with 0.5 La2+ ions in the SrFe12O19 compound, 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. The fully separated double P-E hysteresis loops reveal the antiferroelectrics in La0.5Sr0.5Fe12O19 ceramics. The magnitude of exerting magnetic field enables us to control the generation of spin current, which induces MD and MR effects. A 1.1T magnetic field induces a large spin current of 15.6 n A in La0.5Sr0.5Fe12O19 ceramics, lifts up dielectric constants by 540%, and lowers the resistance by −89%. The magnetic performance remains as usual. The multiple functions in one single phase allow us to develop novel intelligent devices.

Theoretical Study of Electric, Dielectric, and Optical Properties in Ion Doped Multiferroic SrFe12O19 Nanoparticles

“…The occurrence of antiferroelectricity is due to the interruption of translational periodic symmetry on the substituted sites. The observed results are in agreement with the reported experimental data of Huang et al [23], Yin et al [24], Duan et al [25], and Tan et al [26]. Therefore, the FE state of La-doped SFO can be changed by varying the La-doping concentration x which leads to existing of ferromagnetism and antiferroelectricity.…”

“…From Figure 4 it can be seen that ϵ increases with increasing magnetic field h. The stronger the magnetic field, the larger the dielectric constant. This behavior of ϵ(h) is also observed in [23][24][25]. Next, we will consider the properties of a pure SFO NP with ferromagnetic to paramagnetic transition temperature T C f m = 737 K [6].…”

“…In Ni-doped SFO, enhancements in FE polarization, coercivity, and remnant polarizations have been observed [17]. However, in La-doped SFO at the Sr site, La x Sr 1−x Fe 12 O 19 , an intriguing antiferroelectric (AFE) behavior is reported for specific dopant concentrations x (for x = 0.7 by Huang et al [23] and for x = 0.5 by Yin et al [24]).…”

“…The dielectric constant ϵ of La-doped SFO has been thoroughly investigated in various studies [23][24][25]28], for example Ni-doped SFO [17,29], Co-doped SFO [30], Mn-doped SFO [31], and Ca-doped SFO NPs [32]. These investigations explore ϵ as a function of temperature, ion doping concentration, frequency, and magnetic field, shedding light on the intricate interplay between structural, magnetic, and dielectric properties in these materials.…”