Microscopic Origin of Large Negative Magnetoelectric Coupling in<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>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>Ba</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>MnO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>

Giovannetti, Gianluca; Kumar, Sanjeev; Ortix, Carmine; Capone, Massimo; Brink, Jeroen van den

doi:10.1103/physrevlett.109.107601

Cited by 45 publications

(53 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This was attributed to the tendency for 180°Mn-O-Mn bond angles to be favored in the AFM phase, in competition with the polar distortions. [48] To summarize this section, the structural trends in the CaMnO 3 , SrMnO 3 , BaMnO 3 series with both A-site cation and strain that we collected here are exactly as expected based on the increasing A-site cation size down the series. While CaMnO 3 , with its small A-site radius (1.34 Å) and tolerance factor of 0.977 [45] has strong octahedral rotations and tilts and needs large strain values to induce ferroelectricity, BaMnO 3 with its large A site (1.61 Å) and tolerance factor is always ferroelectric and never shows octahedral rotations or tilts.…”

Section: Functional Oxides Prospective Articlesupporting

confidence: 74%

Coupling and competition between ferroelectricity, magnetism, strain, and oxygen vacancies in AMnO3 perovskites

et al. 2016

View full text Add to dashboard Cite

We use first-principles calculations based on density functional theory to investigate the interplay between oxygen vacancies, A-site cation size/tolerance factor, epitaxial strain, ferroelectricity, and magnetism in the perovskite manganite series, AMnO 3 (A = Ca 2+ , Sr). We find that, as expected, increasing the volume through either chemical pressure or tensile strain generally lowers the formation energy of neutral oxygen vacancies consistent with their established tendency to expand the lattice. Increased volume also favors polar distortions, both because competing rotations of the oxygen octahedra are suppressed and because Coulomb repulsion associated with cation off-centering is reduced. Interestingly, the presence of ferroelectric polarization favors ferromagnetic (FM) over antiferromagnetic (AFM) ordering due to suppressed AFM superexchange as the polar distortion bends the Mn-O-Mn bond angles away from the optimal 180°. Intriguingly, we find that polar distortions compete with the formation of oxygen vacancies, which have a higher formation energy in the polar phases; conversely the presence of oxygen vacancies suppresses the onset of polarization. In contrast, oxygen vacancy formation energies are lower for FM than AFM orderings of the same structure type. Our findings suggest a rich and complex phase diagram, in which defect chemistry, polarization, structure, and magnetism can be modified using chemical potential, stress or pressure, and electric or magnetic fields.

show abstract

Section: Functional Oxides Prospective Articlesupporting

confidence: 74%

Coupling and competition between ferroelectricity, magnetism, strain, and oxygen vacancies in AMnO3 perovskites

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Such half-filled correlated electronic configuration is indeed common to Mott multiferroic materials [29,30] in which however the ferroelectric state is realized in a strongly insulating system. While the presence of ferroelectric distortions in Mott insulators is not surprising, the existence of polar distortions in a metal is a remarkable result which still requires a complete understanding.…”

Section: Density Functional and Dynamical Mean Fieldmentioning

confidence: 91%

Electronic correlations in the ferroelectric metallic state ofLiOsO3

et al. 2016

View full text Add to dashboard Cite

LiOsO3 has been recently identified as the first unambiguous "ferroelectric metal", experimentally realizing a prediction from 1965 by Anderson and Blount. In this work, we investigate the metallic state in LiOsO3 by means of infrared spectroscopy supplemented by Density Functional Theory and Dynamical Mean Field Theory calculations. Our measurements and theoretical calculations clearly show that LiOsO3 is a very bad metal with a small quasiparticle weight, close to a Mott-Hubbard localization transition. The agreement between experiments and theory allows us to ascribe all the relevant features in the optical conductivity to strong electron-electron correlations within the t2g manifold of the osmium atoms. Introduction -Ferroelectric materials display a spontaneous polarization due to an inversion symmetry breaking induced by the macroscopic ordering of local dipole moments. Multiferroic materials are defined by coexistent and coupled magnetic and ferroelectric order. It is a natural expectation that ferroelectric (and consequently multiferroic) ordering can only happen in insulators in order to avoid the metallic charge carriers to screen out the ferroelectric polarization. The existence of "ferroelectric metals" challenging this expectation has been hypothesized in 1965 by Anderson and Blount [1], who have shown that ferroelectricity can occur in a metal as long as the electrons at the Fermi level are decoupled from the ferroelectric distortions. Under these circumstances, the ferroelectric ordering can take place through a second-order transition. In 2013 the first unambiguous realization of this proposal has been reported in LiOsO 3 , where a second-order transition leads to a ferroelectric ionic structure below 140 K while the material remains conducting [2]. This behavior is accompanied by a large residual resistivity which exceeds by two orders of magnitude that of prototypical metals as gold, and by a CurieWeiss like behavior of the magnetic susceptibility in the ordered phase which suggests the presence of almost localized magnetic moments, characteristic precursors of Mott localization [2].

show abstract

“…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 .…”

mentioning

confidence: 99%

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

et al. 2015

View full text Add to dashboard Cite

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...

show abstract

Microscopic Origin of Large Negative Magnetoelectric Coupling inSr1/2Ba1/2MnO3

Cited by 45 publications

References 39 publications

Coupling and competition between ferroelectricity, magnetism, strain, and oxygen vacancies in AMnO3 perovskites

Coupling and competition between ferroelectricity, magnetism, strain, and oxygen vacancies in AMnO3 perovskites

Electronic correlations in the ferroelectric metallic state ofLiOsO3

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

Contact Info

Product

Resources

About