Large magnetoresistance in antiferromagnetic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">CaMnO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn><mml:mi mathvariant="normal">−</mml:mi><mml:mi mathvariant="normal">δ</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>

Zeng, Z.; Greenblatt, Martha; Croft, Mark

doi:10.1103/physrevb.59.8784

Cited by 147 publications

(132 citation statements)

References 25 publications

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“…We first discuss the changes in the Mn valence state and conduction-band orbital energetics as a function of in-plane strain. The excess charge associated with a neutral oxygen vacancy in CaMnO3 is accommodated in the lattice via the reduction of two Mn 4+ to Mn 3+ on sites adjacent to the vacancy 24 . Tensile strain thus lowers the oxygen vacancy formation energy since the expanded lattice facilitates the increase in ionic radius associated with these reduction reactions 15 .…”

Section: Textmentioning

confidence: 99%

Strain-Engineered Oxygen Vacancies in CaMnO₃ Thin Films

et al. 2017

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We demonstrate a novel pathway to control and stabilize oxygen vacancies in complex transition-metal oxide thin films. Using atomic layer-by-layer pulsed laser deposition (PLD) from two separate targets, we synthesize high-quality singlecrystalline CaMnO 3 films with systematically varying oxygen vacancy defect formation energies as controlled by coherent tensile strain. The systematic increase of the oxygen vacancy content in CaMnO 3 as a function of applied in-plane strain is observed and confirmed experimentally using high-resolution soft X-ray absorption spectroscopy (XAS) in conjunction with bulk-sensitive hard X-ray photoemission spectroscopy (HAXPES). The relevant defect states in the densities of states are identified and the vacancy content in the films quantified using the combination of first-principles theory and core−hole multiplet calculations with holistic fitting. Our findings open up a promising avenue for designing and controlling new ionically active properties and functionalities of complex transition-metal oxides via strain-induced oxygen-vacancy formation and ordering.

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Section: Textmentioning

confidence: 99%

Strain-Engineered Oxygen Vacancies in CaMnO₃ Thin Films

et al. 2017

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“…We begin by reviewing the behavior of CaMnO 3 , for which the strain dependence of both the intrinsic structure [19,20] and the defect formation energies [18] have been previously studied. CaMnO 3 maintains the a − a − c + tilt system of its bulk orthorhombic perovskite structure [21,22] over the whole range of accessible strains, lowering its symmetry from Pbnm to Pmc2 1 [For our choice of calculation parameters we find the Pmc2 1 phase to be slightly (<1 meV per formula unit) lower in energy than the Pmc2 1 .] when it becomes ferroelectric at a predicted tensile strain value of a few percent; at the largest tensile strains achieved experimentally to date (2.1%) incipient ferroelectricity has been observed.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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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.

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“…Substitution of calcium for higher-charged cations and formation of vacancies in the oxygen sub-lattice both result in partial reduction of Mn 4+ to Mn 3+ cations and appearance of n-type conductivity [1][2][3][4][5][6]. The electrondoped derivatives Ca 1−x R x MnO 3−δ , where R is a rare earth metal, are stable in different atmospheres and exhibit rather large values of conductivity (σ) and negative thermopower (S) up to 1000°C.…”

Section: Introductionmentioning

confidence: 99%

Electron transport in CaMnO3 − δ at elevated temperatures: a mobility analysis

Goldyreva

Леонидов

Патракеев

et al. 2013

J Solid State Electrochem

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The drift mobility of electron charge carriers in oxygen non-stoichiometric manganite CaMnO 3− δ was calculated by combining the total electrical conductivity and oxygen non-stoichiometry data at 700-950°С and oxygen partial pressure varying between 10 −6 and 1 atm. The carrier concentration changes with pressure and temperature were obtained with the help of the earlier-developed defect model involving reactions of oxygen exchange and thermal excitation of manganese sites. The activation energy for mobility is found to increase with oxygen non-stoichiometry. High-temperature electron transport properties of the manganite CaMnO 3−δ can be explained in terms of activated jumps of n-type small polarons in adiabatic regime. The relatively small mobility of charge carriers is explained by strong localization of polarons on manganese sites.

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Large magnetoresistance in antiferromagneticCaMnO3−δ

Cited by 147 publications

References 25 publications

Strain-Engineered Oxygen Vacancies in CaMnO₃ Thin Films

Strain-Engineered Oxygen Vacancies in CaMnO₃ Thin Films

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

Electron transport in CaMnO3 − δ at elevated temperatures: a mobility analysis

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Large magnetoresistance in antiferromagneticCaMnO3−δ

Cited by 147 publications

References 25 publications

Strain-Engineered Oxygen Vacancies in CaMnO3 Thin Films

Strain-Engineered Oxygen Vacancies in CaMnO3 Thin Films

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

Electron transport in CaMnO3 − δ at elevated temperatures: a mobility analysis

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Product

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Strain-Engineered Oxygen Vacancies in CaMnO₃ Thin Films

Strain-Engineered Oxygen Vacancies in CaMnO₃ Thin Films