Strain relaxation in the epitaxy of La2/3Sr1/3MnO3grown by pulsed-laser deposition on SrTiO3(001)

Maurice, Jean‐Luc; Pailloux, F.; Barthélémy, A.; Durand, Olivier; Imhoff, D.; Lyonnet, R.; Rocher, A.; Contour, J. P.

doi:10.1080/14786430310001603436

Cited by 96 publications

(107 citation statements)

References 40 publications

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“…This can be interpreted as follows: on one hand, the slight disagreement between experimental and theoretical c values might be due to non-perfect experimental samples. In fact, it is well known that twin-like defects [11] or oxygen lack -or excess -can often occur as a result of the different growth conditions. The experimental films might therefore show a non-perfect stoichoimetry or a non-high-quality crystallinity (at variance with our simulated perfect crystal), therefore resulting in slightly different lattice constants.…”

Section: Structural Equilibrium Propertiesmentioning

confidence: 99%

“…unstrained) lattice constant was estimated as the weighted average between the experimental lattice parameter of the constituents, LaMnO 3 and SrMnO 3 and is evaluated as a eq = 3.874Å. [11] First of all, as expected from elasticity theory, the c parameter decreases as the strain becomes more and more tensile. However, both from the theoretical and experimental point of view, the lack of a constant volume shows that the material does not behave as an ideal elastic medium: the more compressive (tensile) is the strain, the smaller (larger) is the volume.…”

Section: Structural Equilibrium Propertiesmentioning

confidence: 99%

“…Moreover, it is mandatory for industrial applications to achieve a good control over the film growth, which in turn requires a careful choice of appropriate substrates to get optimized LSMO films. High-performance epitaxial manganites thin films have been successfully grown on [001]-oriented oxides, such as LaAlO 3 (LAO) [6,10], La 0.3 Sr 0.7 Al 0.35 Ta 0.35 O 9 (LSAT) [6], NdGaO 3 (NGO) [6], and SrTiO 3 (STO) [4,11,12]. Strained manganites epilayers often show a different behavior with respect to the bulk.…”

Section: Introductionmentioning

confidence: 99%

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Ab initioelectronic and magnetic structure in La_0.66Sr_0.33MnO₃: strain and correlation effects

Yang

Picozzi

2006

J. Phys.: Condens. Matter

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Abstract. The effects of tetragonal strain on electronic and magnetic properties of strontium-doped lanthanum manganite, La 2/3 Sr 1/3 MnO 3 (LSMO), are investigated by means of density-functional methods. As far as the structural properties are concerned, the comparison between theory and experiments for LSMO strained on the most commonly used substrates, shows an overall good agreement: the slight overestimate (at most of 1-1.5 %) for the equilibrium out-of-plane lattice constants points to possible defects in real samples. The inclusion of a Hubbard-like contribution on the Mn d states, according to the so-called "LSDA+U" approach, is rather ineffective from the structural point of view, but much more important from the electronic and magnetic point of view. In particular, full half-metallicity, which is missed within a bare densityfunctional approach, is recovered within LSDA+U, in agreement with experiments. Moreover, the half-metallic behavior, particularly relevant for spin-injection purposes, is independent on the chosen substrate and is achieved for all the considered in-plane lattice constants. More generally, strain effects are not seen to crucially affect the electronic structure: within the considered tetragonalization range, the minority gap is only slightly (i.e. by about 0.1-0.2 eV) affected by a tensile or compressive strain. Nevertheless, we show that the growth on a smaller in-plane lattice constant can stabilize the out-of-plane vs in-plane e g orbital and significatively change their relative occupancy. Since e g orbitals are key quantities for the double-exchange mechanism, strain effects are confirmed to be crucial for the resulting magnetic coupling.

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Section: Structural Equilibrium Propertiesmentioning

confidence: 99%

Section: Structural Equilibrium Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ab initioelectronic and magnetic structure in La_0.66Sr_0.33MnO₃: strain and correlation effects

Yang

Picozzi

2006

J. Phys.: Condens. Matter

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“…The positions of the Mn L 2,3 edges are known to be related to the Mn oxidation state. 9,[15][16][17][18][19][20] In Fig. 3 we show representative EELS spectra of 3.…”

Section: Fig 1 ͑Color Online͒ ͑A͒mentioning

confidence: 99%

Cationic and charge segregation in La2/3Ca1/3MnO3 thin films grown on (001) and (110) SrTiO3

Estradé

Arbiol

Peiró

et al. 2008

Applied Physics Letters

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Electron energy-loss spectroscopy is used to map composition and electronic states in epitaxial La 2/3 Ca 1/3 MnO 3 films grown on SrTiO 3 ͑001͒ and ͑110͒ substrates. It is found that in partially relaxed ͑110͒ films cationic composition and valence state of Mn 3+/4+ ions are preserved across the film thickness. In contrast, in fully strained ͑001͒ films, the Ca/La ratio gradually changes across the film, being La rich at film/substrate interface and La depleted at free surface; Mn valence state changes accordingly. These observations suggest that a strongly orientation-dependent adaptative composition mechanism dominates stress accommodation in manganite films and provides microscopic understanding of their dissimilar magnetic properties. ͒ / STO/ LSMO system but found a weak decrease in the Mn valence near the interfaces, attributed to a transfer of electrons from STO to LSMO. It has been observed that in LCMO films grown on LaAlO 3 substrates, which are under compressive strain, the La 3+ ions migrate toward the top layer surface. 9 Little attention was received, so far, by the chemistry and electronic structure of ͑110͒ LCMO films, reported to display enhanced magnetic properties when compared to their ͑001͒ counterparts. 10,11 In this work, we report detailed transmission electron microscopy ͑TEM͒ and EELS analyses of epitaxial LCMO layers grown simultaneously on ͑001͒ and ͑110͒ STO substrates.The ͑001͒ and ͑110͒ LCMO layers were grown by rf sputtering at 800°C, at 330 mtorr, with an O 2 / Ar pressure ratio of 1 4 and a growth rate of ϳ0.4 nm/ min. After growth, in situ annealing was performed at 800°C for 1 h in O 2 atmosphere at 350 torr. 10 The magnetic properties of these films have been previously studied. 10,11 both magnetization ͓Fig. 1͑a͔͒ and Curie temperature of the ͑110͒ films are much larger than those of their ͑001͒ counterparts. LCMO films, when grown on ͑001͒ and ͑110͒ STO substrates, have identical ͑tensile͒ lattice mismatch ͑ϳ1.1%͒. However, whereas in-plane orthogonal directions ͓100͔ and ͓010͔ of ͑001͒ films are equivalent, ͓001͔ and ͓110͔ directions are not equivalent a͒ Electronic mail: sestrade@el.ub.es.FIG. 1. ͑Color online͒ ͑a͒ Magnetization vs field curves in the −1 -20 kOe range for ͑001͒ LCMO ͑squares͒ and ͑110͒ LCMO ͑triangles͒ 80 nm films measured at 10 K. Magnetic field was applied in-plane of the samples, being parallel to ͓100͔ direction for the ͑001͒ films and to ͓001͔ direction for the ͑110͒ film. Inset: Normalized XRR spectra from ͑001͒ ͑squares͒ and ͑110͒ ͑triangles͒ 85 nm films. ͑b͒ g = ͑1-10͒ and ͑c͒ g = ͑011͒ two beam images of ͓110͔ LCMO/STO in PV geometry.

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“…Strain gradients in the crystalline structure can be due to local crystal defects such as oxygen vacancies, 16 lattice relaxation at the surface and crystalline dislocations (both generating polarization instability), 17 chemical fluctuations in cationic segregation, 18 impurities, 19 and lattice mismatch of heteroepitaxial films at the substrate. 20 For a centrosymmetric crystal subjected to inhomogeneous deformation, only the strain gradient contributes to the polarization and thus the flexoelectric effect can be investigated independently.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale electromechanical properties of CaCu3Ti4O12 ceramics

Tararam

Bdikin

Panwar

et al. 2011

Journal of Applied Physics

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Piezoresponse Force Microscopy (PFM) is used to characterize the nanoscale electromechanical properties of centrosymmetric CaCu 3 Ti 4 O 12 ceramics with giant dielectric constant. Clear PFM contrast both in vertical (out-of-plane) and lateral (in-plane) modes is observed on the ceramic surface with varying magnitude and polarization direction depending on the grain crystalline orientation. Lateral signal changes its sign upon 180 rotation of the sample thus ruling out spurious electrostatic contribution and confirming piezoelectric nature of the effect. Piezoresponse could be locally reversed by suitable electrical bias (local poling) and induced polarization was quite stable showing long-time relaxation ($3 hrs). The electromechanical contrast in unpoled ceramics is attributed to the surface flexoelectric effect (strain gradient induced polarization) while piezoresponse hysteresis and ferroelectric-like behavior are discussed in terms of structural instabilities due to Ti off-center displacements and structural defects in this material.

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Strain relaxation in the epitaxy of La_2/3Sr_1/3MnO₃grown by pulsed-laser deposition on SrTiO₃(001)

Cited by 96 publications

References 40 publications

Ab initioelectronic and magnetic structure in La_0.66Sr_0.33MnO₃: strain and correlation effects

Ab initioelectronic and magnetic structure in La_0.66Sr_0.33MnO₃: strain and correlation effects

Cationic and charge segregation in La2/3Ca1/3MnO3 thin films grown on (001) and (110) SrTiO3

Nanoscale electromechanical properties of CaCu3Ti4O12 ceramics

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Strain relaxation in the epitaxy of La2/3Sr1/3MnO3grown by pulsed-laser deposition on SrTiO3(001)

Cited by 96 publications

References 40 publications

Ab initioelectronic and magnetic structure in La0.66Sr0.33MnO3: strain and correlation effects

Ab initioelectronic and magnetic structure in La0.66Sr0.33MnO3: strain and correlation effects

Cationic and charge segregation in La2/3Ca1/3MnO3 thin films grown on (001) and (110) SrTiO3

Nanoscale electromechanical properties of CaCu3Ti4O12 ceramics

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Strain relaxation in the epitaxy of La_2/3Sr_1/3MnO₃grown by pulsed-laser deposition on SrTiO₃(001)

Ab initioelectronic and magnetic structure in La_0.66Sr_0.33MnO₃: strain and correlation effects

Ab initioelectronic and magnetic structure in La_0.66Sr_0.33MnO₃: strain and correlation effects