Room-temperature ferroelectricity, superparamagnetism and large magnetoelectricity of solid solution PbFe1/2Ta1/2O3 with (PbMg1/3Nb2/3O3)0.7(PbTiO3)0.3

Giant Magnetoelectric Response in Multiferroics with Coexistence of Superparamagnetic and Ferroelectric Phases at Room Temperature

“…Recently, the results obtained by us with other coauthors had shown [2] that this condition can be fulfilled in multiferroics in which the superparamagnetic and ferroelectric phases coexist. The detailed experimental and theoretical investigations of the ceramic solid solutions PbFe 1/2 Ta 1/2 O 3 with (PbMg 1/3 Nb 2/3 O 3 ) 0.7 (PbTiO 3 ) 0.3 [(PFT) (PMN 0.7 PT 0.3 ) 1− ] had shown that this single-phase multiferroic with ferroelectric and superparamagnetic phases has a nonlinear paramagnetoelectric ME response three thousands times larger than that in broadest known earlier magnetoelectric materials.…”

“…Superparamagnetism has been observed not only in the powders of magnetic nanoparticles, but also in the nanocomposites on particles submerged into a polymeric matrix [3] or those located in the nanopores of non-magnetic materials [4]. It was shown recently [2] that the superparamagnetic phase can be obtain also in a single-phase ceramics like (PFT) (PMN 0.7 PT 0.3 ) 1− ( = 0.5, 0.4), in which Xray data indicate that the ceramic micro-grains consist of nanosize structural units. The superparamagnetic behavior of the magnetization in an external magnetic field for the above-mentioned single phase ceramics and for the nanocomposite on the base of a powder sample of nanoporous carbon filled by Ni particles can be seen in Figs.…”

“…The parameters of a fitting in the case of multiferroic (PFT) (PMN 0.7 PT 0.3 ) 1− are given in [2]. In what follows, we will pay the most attention namely to this material because of the coexistence of electric polarization and magnetization necessary for the magnetoelectric effect in it, whereas there is only the magnetization in nanocomposites on the base of carbon particles.…”

“…To throw light on the physical mechanism of a possible large magnetoelectric effect in multiferroics with the coexistence of superparamagnetism and ferroelectricity we will follow the results obtained in [2]. Within the phenomenological Landau-Ginzburg-Devonshire (LGD) approach, the contributions of the linear and biquadratic ME couplings to the free energy of the system are described by the terms and , respectively ( is the polarization component and is the magnetization one, and and are corresponding tensors of linear and biquadratic ME couplings, respectively) [5][6][7].…”

“…The aim of such approach is to find out the possible group of other materials with the coexistence of superparamagnetic and ferroelectric phases at room temperature. Since we are going to pay attention mainly to magnetic and magnetoelectric properties of (PFT) (PMN 0.7 PT 0.3 ) 1− , we recommend the readers to find technological details of the preparation of samples and the investigation of their structure in [2]. In particular, X-ray data had shown that the ceramic micrograins consist of nanoscale structural units.…”