Ferroelectricity in the 1 μ C cm−2 range induced by canted antiferromagnetism in (LaMn3)Mn4O12

Abstract

Pyroelectric current and field-dependent specific heat measurements on polycrystalline samples of the quadruple perovskite (LaMn3)Mn4O12 give evidence of ferroelectricity driven by the canted antiferromagnetic ordering of the B-site Mn3+ ions at TN,B=78 K with record large remnant electric polarization up to 0.56 μC cm−2. X-ray diffraction measurements indicate an anomalous behavior of the monoclinic β angle at TN,B, which suggests that the polarization lies in the ac-plane, where the moments are collinear, and that symmetric exchange striction is the mechanism of spin-driven ferroelectricity. Polarization values up to ∼3–6 μC cm−2 are expected in single crystals or epitaxial films, which would enable the development of practical multiferroic applications.

Unconventional magnetic ferroelectricity in the quadruple perovskite NaMn7O12

“…3. According to the first scenario that invokes an enhancement of the canted component of the AFM structure at T * , the symmetric exchange interaction associated with this component would be the driving mechanism of ferroelectricity, as already proposed for both CaMn 7 O 12 [13] and LaMn 7 O 12 [4]. The second scenario of net magnetization at the domain boundary is consistent with a theoretical model of AFM magnetoelectrics predicting the formation of a net magnetization at the AFM domain boundary [38].…”

“…Manganese oxides, such as simple perovskites REMnO 3 (RE = rare earth) with non-collinear E-type antiferromagnetic (AFM) structure [1] and quadruple perovskites AMn 7 O 12 (A=Ca, La) with canted AFM structure [2][3][4][5], have attracted a great deal of interest for they display enhanced magnetic ferroelectricity (MF). Among these compounds, LaMn 7 O 12 , first reported by Bochu et al [6], exhibits record values of remanent polarization at saturation as high as 0.56 µC cm −2 in polycrystalline samples [4]. Even higher values 1-10 µC cm −2 are expected in single crystals or epitaxial films, which may enable the realization of novel applications like fast, nonvolatile and low-energy-consumption memories [7][8][9].…”

“…A further issue is the controversial contribution of the antisymmetric or symmetric exchange interactions to the electric polarization [11][12][13] and the possible role of charge order [14,15]. The existence of a pronounced canting of the AFM structure in both CaMn 7 O 12 and LaMn 7 O 12 , caused by a strong Dzyaloshinskii-Moriya interaction, led various authors to propose that the symmetric exchange interaction should be the dominant mechanism of ferroelectricity in the AMn 7 O 12 system [4,13,15]. However, the complex structural modulations concomitant to the magnetic order observed in the most studied compound CaMn 7 O 12 [16] prevents to establish clear relationships between ferroelectric and magnetic properties.…”

“…The presence of two distinct A and A sites enables to obtain mixed-valence properties without introducing disorder or chemical inhomogeneities inherent to chemically-substituted ABO 3 compounds like manganites [20] or nickelates [21]. These unique characteristics may be the key to explain the variety of unique charge, orbital and spin ordering phenomena observed in QP compounds [22][23][24] as well as the aforementioned remarkable enhancement of magnetic ferroelectricity in the restricted QP AMn 7 O 12 family, where both A and B sites are occupied by Mn [4,5,25,26].…”

Pressure-induced structural phase transition and suppression of Jahn-Teller distortion in the quadruple perovskite structure

“…The above unique features may explain the fact that the QP manganites (AMn 3 )Mn 4 O 12 exhibit almost full charge, spin and orbital orderings with sharp phase transitions and no coexistence of the disordered phase. [7] Recently, these manganites have attracted further interest for the record value of electric polarizations induced by magnetic order reported for A=Ca [9] and A=La [10].…”