Displacement-Type Ferroelectricity with Off-Center Magnetic Ions in Perovskite<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Sr</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo mathvariant="bold">−</mml:mo><mml:mi mathvariant="bold-italic">x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Ba</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>MnO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>

Sakai, Hideaki; Fujioka, Jun; Fukuda, Tatsuo; Okuyama, Daisuke; Hashizume, Daisuke; Kagawa, Fumitaka; Nakao, Hironori; Murakami, Youichi; Arima, T.; Baron, Alfred Q. R.; Taguchi, Y.; Tokura, Y.

doi:10.1103/physrevlett.107.137601

Cited by 157 publications

(158 citation statements)

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“…For bulk SrMnO 3 this prediction was confirmed by partial substitution of Sr by Ba which induces negative chemical pressure and leads to a polar state 10 . According to DFT, epitaxial SrMnO 3 films should develop a polarisation along one of the pseudocubic <110> axes under >1% epitaxial tensile strain 8 .…”

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confidence: 79%

“…The relation between polar order and strain is cross-checked by confirming the absence of a SHG signal on a centrosymmetric SrMnO 3 polycrystal. Comparison to Sr 0.5 Ba 0.5 MnO 3 furthermore allows us to associate the decrease of the SHG signal in the strained SrMnO 3 films below 250 K to the multiferroic onset of antiferromagnetic order which reduces the spontaneous polarisation 10,12 .…”

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confidence: 99%

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Strain-induced coupling of electrical polarization and structural defects in SrMnO3 films

et al. 2015

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Local perturbations in complex oxides such as domain walls 1,2 , strain 3,4 and defects 5,6 are of interest because they can modify the conduction or the dielectric and magnetic response and even promote phase transitions. Here we show that the interaction between different types of local perturbations in oxide thin films is an additional source of functionality. Taking SrMnO 3 as a model system, we use nonlinear optics to verify the theoretical prediction that strain induces a polar phase, and density functional theory to show that strain simultaneously increases the concentration of oxygen vacancies. These vacancies couple to the polar domain walls where they establish an electrostatic barrier to electron migration. The result 2 is a state with locally structured room-temperature conductivity consisting of conducting nanosized polar domains encased by insulating domain boundaries, which we resolve using scanning probe microscopy. Our "nanocapacitor" domains can be individually charged, suggesting stable capacitance nanobits with a potential for information storage technology.At first we verify the occurrence of strain-induced polar order in SrMnO 3 thin films.Motivated by the search for novel multiferroic materials, which combine magnetic and ferroelectric orders in the same phase, density functional theory (DFT) predicted the occurrence of ferroelectricity in the perovskite-structure alkaline-earth manganites at larger-than-equilibrium lattice parameters 7,8,9 . For bulk SrMnO 3 this prediction was confirmed by partial substitution of Sr by Ba which induces negative chemical pressure and leads to a polar state 10 . According to DFT, epitaxial SrMnO 3 films should develop a polarisation along one of the pseudocubic <110> axes under >1% epitaxial tensile strain 8 .20-nm films of single-phase SrMnO 3 were grown using pulsed laser deposition on (001)-oriented (LaAlO 3 ) 0.3 (Sr 2 AlTaO 6 ) 0.7 (LSAT) with 1.7% tensile strain (see Methods). We characterised the strain state of the films using scanning transmission electron microscopy (STEM) and X-ray and electron diffraction. Figure 1a shows a cross-sectional STEM image evidencing the high quality of the films on the atomic scale with a sharp SrMnO 3 /LSAT (001) interface. The reciprocal space map in Fig. 1a verifies that the films are tetragonal and coherently strained. The electron diffraction In the anisotropy plot in Fig. 1c we present the optical polarisation analysis of the SHG signal obtained on a test area of 0.1 mm 2 . We fitted the angular dependence of the SHG signal by assuming a distribution of four polar domain states denoted as P 1+ , P 1− , P 2+ , P 2− . The indices refer to the orientation of the polar axis according to 1 ± ↔ ±[110] and 2 ± ↔ ±[1 10], see Fig. 1c. The coincidence of the measured data and the fit is excellent with a fitted ratio r = P 1 /P 2 = 0.53 in the population of P 1 -and P 2 -type domain states (r varied between different test areas). In contrast, fits assuming a polarisation along the[100] and [010] directions failed. We co...

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Strain-induced coupling of electrical polarization and structural defects in SrMnO3 films

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“…Work on lightly substituted Sr 1-x Ba x MnO 3 up to a maximum of x≈0.2 with conventional fabrication techniques did not reveal ferroelectricity [9], while more recent work to higher concentrations identified the expected soft phonon that should trigger the ferroelectric order at higher x [10]. Indeed with further increase of Ba robust ferroelectricity has been recently observed [11]. Here we present neutron scattering results for the spin dynamical properties of the type-I multiferroic perovskite Sr 0.56 Ba 0.44 MnO 3 and the coupling of the magnetic order parameter to the ferroelectricity.…”

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confidence: 99%

“…For this work polycrystalline samples of perovskite Sr 1-x Ba x MnO 3 were synthesized using the two-step solid state method described in references [9,11,12], which is required to avoid the more stable hexagonal polymorph and remain in the pseudocubic regime where the ferroelectric order exists. First the hexagonal precursor material was synthesized in flowing H 2 /Ar gas at high temperatures near 1300 C to obtain single-phase oxygen-reduced perovskite samples.…”

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Neutron scattering studies of the ferroelectric distortion and spin dynamics in the type-1 multiferroic perovskiteSr0.56Ba0.44MnO3

et al. 2014

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The magnetic order, spin dynamics, and crystal structure of the multiferroic Sr 0.56 Ba 0.44 MnO 3 have been investigated using neutron and x-ray scattering. Ferroelectricity develops at T C =305 K with a polarization of 4.2 µC/cm 2 associated with the displacements of the Mn ions, while the Mn 4+ spins order below T N  200 K into a simple G-type commensurate magnetic structure. Below T N the ferroelectric order decreases dramatically demonstrating that the two order parameters are strongly coupled. The ground state spin dynamics are characterized by a spin gap of 4.6(5) meV and the magnon density of states peaking at 43 meV. Detailed spin wave simulations with a gap and isotropic exchange of J=4.8(2) meV describe the excitation spectrum well. Above T N strong spin correlations coexist with robust ferroelectric order.

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“…An additional improvement of the fit was achieved by refining the occupations of oxygen sites. One has to note that, according to the structural formula (2) . The number of lithium atoms clearly exceeds the expected value 1.75.…”

Section: Crystal Structurementioning

confidence: 99%

Synthesis and crystal structure of a new hexagonal perovskite 7H-Ba₇Li_1.75Mn_3.5O_15.75with Mn⁴⁺/Mn⁵⁺charge distribution

et al. 2015

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.75 Mn 3.5 O 15.75 is a new hexagonal perovskite whose crystal structure has elements typical for the layered hexagonal perovskites and quasi-one-dimensional oxides, hence representing a new polytype. It has been synthesized via a solid-state microwave route. The crystal structure was solved using a combination of X-ray and neutron diffraction data, which show that Ba 7 Li 1.75 Mn 3.5 O 15.75 crystallizes in a hexagonal unit cell with parameters a = 5.66274(2) Å and c = 16.7467(1) Å (V = 465.063(4) Å 3 ), with one formula unit, and can be described as columns of face-shared octahedra occupied by Mn 4+ and Li + cations and vacancies along the c axis separated in the ab plane by barium atoms. Every sixth layer, the coordination of Mn 5+ and Li + changes to tetrahedral. Additional local ordering of manganese and lithium atoms among cationic sites leading to the formation of a rhombohedral supercell has been observed by scanning transmission electron microscopy.

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Displacement-Type Ferroelectricity with Off-Center Magnetic Ions in PerovskiteSr1−xBaxMnO3

Cited by 157 publications

References 24 publications

Strain-induced coupling of electrical polarization and structural defects in SrMnO3 films

Strain-induced coupling of electrical polarization and structural defects in SrMnO3 films

Neutron scattering studies of the ferroelectric distortion and spin dynamics in the type-1 multiferroic perovskiteSr0.56Ba0.44MnO3

Synthesis and crystal structure of a new hexagonal perovskite 7H-Ba₇Li_1.75Mn_3.5O_15.75with Mn⁴⁺/Mn⁵⁺charge distribution

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Displacement-Type Ferroelectricity with Off-Center Magnetic Ions in PerovskiteSr1−xBaxMnO3

Cited by 157 publications

References 24 publications

Strain-induced coupling of electrical polarization and structural defects in SrMnO3 films

Strain-induced coupling of electrical polarization and structural defects in SrMnO3 films

Neutron scattering studies of the ferroelectric distortion and spin dynamics in the type-1 multiferroic perovskiteSr0.56Ba0.44MnO3

Synthesis and crystal structure of a new hexagonal perovskite 7H-Ba7Li1.75Mn3.5O15.75with Mn4+/Mn5+charge distribution

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Synthesis and crystal structure of a new hexagonal perovskite 7H-Ba₇Li_1.75Mn_3.5O_15.75with Mn⁴⁺/Mn⁵⁺charge distribution