Observation of coupled magnetic and electric domains

Fiebig, Manfred; Lottermoser, Thomas; Fröhlich, D.; Goltsev, A. V.; Pisarev, R. V.

doi:10.1038/nature01077

Cited by 1,455 publications

(896 citation statements)

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“…Recent works reported domain-wall thickness differences between charged an uncharged 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 16 ferroelectric-180º and ferroelastic-90º walls quantitatively measured at the atomic scale in epitaxial PbTiO 3 thin films 41,42 , in which the strong depolarizing field of the head-to-head dipoles is stabilized by distributing the polarization charge over an extended thickness 41,45 . However, in multiferroic materials domain walls are generally thicker than in normal ferroelectrics which may depend on the degree of coupling and correlation length between the two ferroic orders 11,[46][47][48] . Herein, moreover, high-polar and low-polar state domains can interact together with the presence of in-plane and out-of-plane polarization gradients.…”

Section: Textmentioning

confidence: 99%

Polar-Graded Multiferroic SrMnO₃ Thin Films

et al. 2016

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Engineering defects and strains in oxides provides a promising route for the quest of thin film materials with coexisting ferroic orders, multiferroics, with efficient magnetoelectric coupling at room temperature. Precise control of the strain gradient would enable custom tailoring of the multiferroic properties, but presently remains challenging. Here we explore the existence of a polar-graded state in epitaxially-strained antiferromagnetic SrMnO 3 thin films, whose polar nature was predicted theoretically, and recently demonstrated experimentally. By means of aberration-corrected scanning transmission electron microscopy we map the polar rotation of the ferroelectric polarization at atomic resolution, both far from and near the domain walls and find flexoelectricity resulting from vertical strain gradients. The origin of this particular strain state is a gradual distribution of oxygen vacancies across the film thickness, according to electron energy loss spectroscopy. Herein we present a chemistry-mediated route to induce polar rotations in oxygen-deficient multiferroic films, resulting in flexoelectric polar rotations and with potentially enhanced piezoelectricity. KEYWORDS: Multiferroics, ferroelectricity, flexoelectricity, aberration-corrected STEM, domain walls. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 4 TEXT Multiferroic materials have attracted great interest recently because of their intriguing fundamental physics and the wide range of potential applications such as transducers and information storage [1][2][3] . Of particular technological impact is the search for materials showing efficient coupling between ferromagnetic and ferroelectric orders that persist at room temperature. Manganese-based perovskite oxides AMnO 3 , A being an alkaline-earth cation, are particularly promising for this purpose; theoretical calculations reveal the onset of a ferroelectric ground state with strong magnetoelectric coupling since the spontaneous polarization is expected to be driven by the off-centering of the magnetic Mn 4+ ion 4,5 . The ferroelectric instability is predicted to increase by expansion of the lattice and, in turn, strain-induced ferroelectricity was experimentally demonstrated in Ba-substituted SrMnO 3 single crystals, in which chemical expansion of the crystal lattice is caused by partially replacing Sr with larger Ba ions 6 .Alternatively, strains can be induced into films through the use of epitaxial growth and can be utilized to modify the ferroelectric film properties by an adequate choice of the substrate 7-9 . In particular, strain-engineering of multiferroism has opened a path for the e...

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Section: Textmentioning

confidence: 99%

Polar-Graded Multiferroic SrMnO₃ Thin Films

et al. 2016

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“…Of these materials YMnO 3 , with a layered structure with Y ions placed between sheets of corner sharing MnO 5 triangular bipyramids, has been of particular interest [9][10][11][12][13][14][15][16]. It is ferroelectric (FE) below ∼900-1300 K and antiferromagnetic (AFM) below ∼75 K [15].…”

Section: Introductionmentioning

confidence: 99%

“…Bilinear coupling between the magnetic (AFM) and ferroelectric order parameters is symmetry forbidden but magnetoelectric effects have nevertheless been observed. In particular, Fiebig et al [11] observed coupling of antiferromagnetic and ferroelectric order parameters at the ferroelectric domain boundaries. The explanation for the origin of this magnetoelectric effect has been suggested to be the interaction between ferroelectric (FE) and antiferromagnetic (AFM) domain walls.…”

Section: Introductionmentioning

confidence: 99%

“…The opposing polarization of neighbouring FE domains induces a strain at the domain wall while the gradual rotation of the magnetic moments across an AFM domain wall causes a local magnetic moment. These two effects can interact via the piezomagnetic effect, 'clamping' AFM and FE domain walls together such that any reversal of FE order triggers a reversal of AFM order via the induced strain [8,11,17]. Alternatively, theory has shown that 'clamping' of the magnetic and ferroelectric order parameters may be caused by the effect of a Dzyaloshinsky-Moriya interaction, which was found to operate within a domain boundary and cause a reversal of the spin direction across an FE wall [18].…”

Section: Introductionmentioning

confidence: 99%

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Elastic anomalies associated with structural and magnetic phase transitions in single crystal hexagonal YMnO₃

Thomson

Chatterji

Howard

et al. 2014

J. Phys.: Condens. Matter

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Resonant ultrasound spectroscopy has been used to measure the elastic and anelastic behaviour through known structural and magnetic phase transitions in single crystal hexagonal YMnO 3 . Anomalous elastic behaviour is observed at the high temperature structural transition at ∼1260 K, with a discontinuity in the elastic constants and nonlinear recovery below T c , consistent with λeQ 2 s coupling. There is no change in dissipation associated with this high temperature transition, and no evidence in the elastic or anelastic behaviour for any secondary transition at ∼920 K, thus supporting the thesis of a single high temperature transformation. Elastic stiffening is observed on cooling through T N , in accordance with previous studies, and the excess elastic constant appears to scale with the square of the magnetic order parameter. The strains incurred at T N are a factor of ∼20 smaller than those at the structural transition, implying very weak λeQ 2 m coupling and a dominant contribution to the variation in the elastic constants from λe 2 Q 2 m . The increased acoustic dissipation above T N is consistent with an order-disorder process.

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“…Magnetoelectric effects in many of the materials therefore occur by alternative mechanisms. Thus, magnetoelectric properties of rare earth manganates such as YMnO 3 , TbMnO 3 and YMn 2 O 5 arise due to the tilting of polyhedra or frustrated magnetism [6][7][8].…”

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confidence: 99%

Multiferroic nature of charge-ordered rare earth manganites

Serrao¹,

Sundaresan²,

Rao³

2007

J. Phys.: Condens. Matter

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The present study of the charge-ordered manganites shows that many of the chargeordered rare earth manganites are multiferroics showing magnetocapacitance. They also show exhibit certain other features. Thus, the broad maximum in the dielectric constant around T CO or T N becomes more prominent in the presence of the magnetic field in certain cases. The magnitude and sign of the magnetocapacitance effect depends on the frequency of measurement. It is generally better to employ a relatively high frequency, well above 10k Hz to obtain reliable data.We have also studied the dielectric properties of a few other charge-ordered rare earth manganites, La 0.25 Nd 0.25 Ca 0.5 MnO 3 being one of them. This material exhibits a re-entrant 4 ferromagnetic transition at a temperature lower than the charge-ordered transition. The chargeordered transition is around 240 K and the ferromagnetic transition is at 150 K [15]. Interestingly, we find maxima in the dielectric constant at both T CO and T N , the one at T CO being is more prominent (figure 4).It is important to note some of the important characteristics of the charge-ordered manganites studied by us in order to fully understand their ferroic properties. The most important feature is that all these manganites exhibit electronic phase separation at low temperatures (T < T CO ) [10]. They exhibit a decrease in resistivity on application of large magnetic fields (>4 T) [16,17]. Application of electric fields also causes a significant decrease in the resistivity of the manganites [17,18]. On the application of electric fields, the manganites show magnetic response [19]. Such electric field-induced magnetization may also be taken as evidence for coupling between the electric and magnetic order parameters in the manganites. It is likely that grain boundaries between the different electronic phases have a role in determining the dielectric behaviour. The importance of grain boundaries in giving rise to high dielectric constants has indeed been recognized [20,21]. In spite of the complexity of their electronic structure, the present study shows that the charge-ordered rare earth manganites possess multiferroic and magnetoelectric properties. Clearly, charge-ordering provides a novel route to multiferroic properties specially in the case of the manganites. Acknowledgement:

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Observation of coupled magnetic and electric domains

Cited by 1,455 publications

References 14 publications

Polar-Graded Multiferroic SrMnO₃ Thin Films

Polar-Graded Multiferroic SrMnO₃ Thin Films

Elastic anomalies associated with structural and magnetic phase transitions in single crystal hexagonal YMnO₃

Multiferroic nature of charge-ordered rare earth manganites

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Observation of coupled magnetic and electric domains

Cited by 1,455 publications

References 14 publications

Polar-Graded Multiferroic SrMnO3 Thin Films

Polar-Graded Multiferroic SrMnO3 Thin Films

Elastic anomalies associated with structural and magnetic phase transitions in single crystal hexagonal YMnO3

Multiferroic nature of charge-ordered rare earth manganites

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About

Polar-Graded Multiferroic SrMnO₃ Thin Films

Polar-Graded Multiferroic SrMnO₃ Thin Films

Elastic anomalies associated with structural and magnetic phase transitions in single crystal hexagonal YMnO₃