Magnetoelectric Response in Multiferroic SrFe12O19 Ceramics
  We report here the realization of ferroelectricity, ferromagnetism and magnetocapacitance effect in SrFe12O19 ceramics at room temperature. The ceramics demonstrate a saturated polarization hysteresis loop, two I-V peaks and large anomaly of dielectric constant near Curie temperature. These evidences confirmed the ferroelectricity of SrFe12O19 ceramics after annealing in O2 atmosphere. The remnant polarization of the SrFe12O19 ceramic is 103 {\mu}C/cm2. The material also exhibits strong ferromagnetic characterization, the coercive field and remnant magnetic moment are 6192Oe and 35.8emu/g, respectively. Subsequent annealing SrFe12O19 ceramics in O2 not only reveals its innate ferroelectricity but also improves the ferromagnetic properties through transforming Fe2+ into Fe3+. By applying a magnetic field, the capacitance demonstrates remarkable change along with B field, the maximum relative change of dielectric constant is 1174%, which reflects a giant magnetocapacitance effect in SrFe12O19. These combined functional responses in SrFe12O19 ceramics opens substantial possibilities for applications in novel electric devices. 
Guolong Tan, Yao Huang, Haohao Sheng
cond-mat.mtrl-sci