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

Abstract

Multiferroics are materials having two or more order parameters (for instance, magnetic, electric, or elastic) coexisting in the same phase. They have emerged as an important topic in condensed matter physics due to both their intriguing physical behaviors and a broad variety of novel physical applications they enable. Here, we report the results of comprehensive studies of the magnetoelectric (ME) effect in multiferroics with superparamagnetic and ferroelectric phases. On the example of a solid solution of PbFe1/2Ta1/2O3 with (PbMg1/3Nb2/3O3)0.7(PbTiO3)0.3 or Pb(ZrTi)O3, we demonstrate that, in the system with the coexistent superparamagnetic and ferroelectric phases, the ME coefficient can be increased up to three orders in magnitude as compared to conventional magnetoelectrics. This is supported by both theoretical calculations and direct measurements of the ME coefficient. Our study demonstrates that multiferroics with superparamagnetic and ferroelectric phases can be considered as promising materials for applications along with composite multiphase (ferroelectric/ferromagnetic) structures.

New trends in the nanophysics of ferroics, relaxors and multiferroics

“…The main attention is paid to spontaneous flexoeffects and reentrant phase in nanoferroics and to recently discovered giant magnetoelectric effect in multiferroics. In particular, ME coefficient measured by the authors of references [23,24] at room temperature is equal to 𝛽 = 0.54•10 −15 s/Å for (PFT) 𝑥 (PMN 0.7 -PT 0.3 ) 1𝑥 while its value for PFN-PT appeared to be much smaller, namely 𝛽 ∼ 10 −18 s/Å and its value for BiFeO 3 is 𝛽 = 2.54 • 10 −19 s/Å. We have to note that both these phenomena (see references [15,18]) as well as the appearance of morphotropic phase in a relaxor due to the influence of the oxygen vacancies (see [22]) were proposed by the author of this review for the first time in the world science.…”

“…The coexistence of ferroelectric and relaxor phases due to oxygen vacancies is considered in [22]. The results of our calculations and comparison of the developed theory with experiment can be found in sections 2, 3 and 4; a giant magnetoelectric effect in multiferroics is presented in section 4.2 and was published in our papers [23,24].…”

“…Let us note that spontaneous flexocoupling was introduced in [17], physical mechanism of reentrant phase appearance was considered in [21], the appearance of morphotropic phase in the relaxor due to oxygen vacancies influence [22], mechanism of giant magnetoelectric coupling appearance as well as the materials of this phenomenon observation [23,24] were proposed by the authors of this review.…”

“…That is why we decided to give a separate introduction and a list of references for the convenience of readers. Moreover, this part is divided into two parts, namely subsection 4.1 based on reference [23] and subsection 4.2 based on reference [24]. The subsections 4.1 and 4.2 differ from one another by the choice of the materials, although the preparation of samples, structural characterization and experimental methods will be the same.…”