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arXiv · 1803.00731

Antiferroelectric and Magnetodielectric Coupling Response of La0.2Sr0.7Fe12O19 Ceramics

Yao Huang·Guolong Tan
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Abstract

Multiferroics is a class of functional materials that simultaneously exhibit ferroelectricity and ferromagnetism in a single structure. We report here the integration of anti-ferroelectricity and ferromagnetism in a new M-type hexaferrite compound, in which 0.3 Sr ions was substituted by 0.2 La3+ ions in SrFe12O19 so as to keep the charge balance. This doped compound is expressed as a molecular formula of La0.2Sr0.7Fe12O19, which was confirmed by XRD to have the same structure as SrFe12O19 with a lattice contraction of 0.59%. Surprisingly, the doping effect turns La0.2Sr0.7Fe12O19 from ferroelectric to antiferroelectric phase, which displays double hysteresis loops with a maximum polarization of 154 uC/cm2 and a remnant one of 38uC/cm2. The dielectric constant is also greatly improved from 1462 to 1451778 at 10.2Hz by this substitution. This compound simultaneously demonstrates strong ferromagnetism, the remnant magnetic moment and coercive field are 52 emu/g and 5876 Oe, respectively. In addition, La0.2Sr0.7Fe12O19 also exhibits strong magnetodielectric (MD) response, in which a applying magnetic field B lifts the whole e1-f spectra up and right shifts e2-f spectra to higher frequency side. Both real and imaginary parts of the dielectric constant varies with frequency and B field and obey Debye relaxation model. The maximum MD increment in e1 reaches as high as 540830 upon a B field of 926mT. The capacitance of the La0.2Sr0.7Fe12O19 ceramics could be much more enhanced by applying a magnetic field B, which could induce an additional polarization P(H) upon the conventional P(E) by the cycloid conical spin in the intermediate phases. These results suggest that La0.2Sr0.7Fe12O19 exhibits a strong interplay between magnetic ordering and ferroelectricity, which makes it a good magnetoelectric coupling candidate.

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Yao Huang, Guolong Tan. 2018-03-02. Antiferroelectric and Magnetodielectric Coupling Response of La0.2Sr0.7Fe12O19 Ceramics. https://arxiv.org/abs/1803.00731

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