Growth control of stoichiometry in LaMnO3 epitaxial thin films by pulsed laser deposition

Marton, Zsolt; Seo, S. S. A.; Egami, T.; Lee, Ho Nyung

doi:10.1016/j.jcrysgro.2010.07.013

Cited by 42 publications

(40 citation statements)

References 29 publications

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“…SrTiO 3 has a cell parameter that would induce the FM half-metallic phase obtained under uniaxial pressure in this work. However, the epitaxial growth of LaMnO 3 on SrTiO 3 induces a FM insulator behavior [53,54], probably due to other mechanisms such as the electron transfer at the interface of both materials.…”

Section: Electronic and Magnetic Properties Under Uniaxial Compresmentioning

confidence: 99%

Uniaxial pressure-induced half-metallic ferromagnetic phase transition inLaMnO3

2016

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We use first-principles theory to predict that the application of uniaxial compressive strain leads to a transition from an antiferromagnetic insulator to a ferromagnetic half-metal phase in LaMnO3. We identify the Q2 Jahn-Teller mode as the primary mechanism that drives the transition, indicating that this mode can be used to tune the lattice, charge, and spin coupling. Applying ≃ 6 GPa of uniaxial pressure along the [010] direction activates the transition to a half-metallic pseudo-cubic state. The half-metallicity opens the possibility of producing colossal magnetoresistance in the stoichiometric LaMnO3 compound at significantly lower pressure compared to recently observed investigations using hydrostatic pressure.

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Section: Electronic and Magnetic Properties Under Uniaxial Compresmentioning

confidence: 99%

Uniaxial pressure-induced half-metallic ferromagnetic phase transition inLaMnO3

2016

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“…In this paper, we grew different thicknesses of [16][17][18][19][20] X-ray diffraction (XRD) and reciprocal space mapping of the annealed superlattices were measured at the synchrotron radiation source at the 10C1 beam-line of the Pohang Accelerator…”

Section: Introductionmentioning

confidence: 99%

Charge states and magnetic ordering in LaMnO3/SrTiO3superlattices

et al. 2011

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We investigated the magnetic and optical properties of [(LaMnO 3 ) n /(SrTiO 3 ) 8 ] 20 (n = 1, 2, and 8) superlattices grown by pulsed laser deposition. We found a weak ferromagnetic and semiconducting state developed in all superlattices. An analysis of the optical conductivity showed that the LaMnO 3 layers in the superlattices were slightly doped. The amount of doping was almost identical regardless of the LaMnO 3 layer thickness up to eight unit cells, suggesting that the effect is not limited to the interface. On the other hand, the magnetic ordering became less stable as the LaMnO 3 layer thickness decreased, probably due to a dimensional effect.

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“…In case of manganite thin films, the growth even in high vacuum yields only perovskite films. [20] Interestingly, the use of an oxygen getter layer next to the manganite film was found to offer a way to stabilizing the Mnbased brownmillerite phase. [21] Since the direct growth of SrCoO x films with x > 2.5 was not possible as also confirmed by previous attempts, [22] we tried in-situ oxygen postannealing in much higher P(O 2 ) to trigger the topotactic oxidation to form SCO phases with x>2.5. contrasts between the octahedral and tetrahedral sub-layers by oxygen intercalation.…”

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Topotactic Phase Transformation of the Brownmillerite SrCoO_2.5 to the Perovskite SrCoO_3–_δ

et al. 2013

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Oxygen stoichiometry is one of the most important elements in determining the physical properties of transition metal oxides (TMOs). A small change in the oxygen content results in the variation of valence state of the transition metal, drastically modifying the materials functionalities. The latter includes, for instance, (super-)conductivity, magnetism, ferroelectricity, bulk ionic conduction, and catalytic surface reactions. [1][2][3][4][5] In particular, among those applications, TMOs with mixed valence states have attracted attention for many environmental and renewable energy applications, including catalysts, hydrogen generation from water splitting, cathodes in rechargeable batteries and solid oxide fuel cells, and oxygen separation membranes. [6][7][8] For example, previous studies have shown that the ability to control the number of d-band electron population and detailed spin configuration in TMOs is critical for improved catalytic performance of TMOs. [9,10] In this context, SrCoO x (2.5 ≤ x ≤ 3.0) is an ideal class of materials to study the evolution of the physical properties by modifying the valence state in TMOs, due to the existence of two structurally distinct topotactic phases, i.e. the brownmillerite SrCoO 2.5 (BM-2 SCO) (see Figure 1a) and the perovskite SrCoO 3 . [11,12] Especially, BM-SCO has atomicallyordered one-dimensional vacancy channels (see Figure 1a), which can accommodate additional oxygen when the valence state of Co is changed. Moreover, SrCoO x exhibits a wide spectrum of physical properties from antiferromagnetic insulator to ferromagnetic metal depending on the oxygen stoichiometry. [11][12][13] Since SrCoO x has only a single control knob, i.e. the oxygen contentx, to modify the Co valence state without cation doping, it is straightforward to study the valence state (i.e. oxygen content) dependent physical properties. However, so far, the growth of high quality single crystalline materials has not been as successful due to difficulty in controlling the right oxidation state.In this work, we report on the epitaxial growth of high quality BM-SCO single crystalline films on SrTiO 3 (STO) substrates by pulsed laser epitaxy (PLE). In order to examine the topotactic phase transformation to the perovskite SrCoO 3- (P-SCO), some of the samples were subsequently in-situ annealed at various oxygen pressure (P(O 2 )) to fill the oxygen vacancies.While the direct growth of P-SCO films with x = 3.0 was an arduous task, we found that postannealing in high P(O 2 ) (> several hundreds of Torr) could fill sufficient amount of oxygen vacancies, yielding systematic evolution in electronic, magnetic, and thermoelectric properties. (Figure 1b) demonstrate that the films are of high quality. X-ray rocking curve ω-scans revealed a full width half maximum (FWHM) of < 0.04º, demonstrating the excellent crystallinity (cf., FWHM of the 002 STO peak was ~0.02º) of our films (data not shown).While we have shown the XRD data from a well-optimized, high quality thin film, it is worthwhile to mention tha...

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Growth control of stoichiometry in LaMnO3 epitaxial thin films by pulsed laser deposition

Cited by 42 publications

References 29 publications

Uniaxial pressure-induced half-metallic ferromagnetic phase transition inLaMnO3

Uniaxial pressure-induced half-metallic ferromagnetic phase transition inLaMnO3

Charge states and magnetic ordering in LaMnO3/SrTiO3superlattices

Topotactic Phase Transformation of the Brownmillerite SrCoO_2.5 to the Perovskite SrCoO_3–_δ

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Growth control of stoichiometry in LaMnO3 epitaxial thin films by pulsed laser deposition

Cited by 42 publications

References 29 publications

Uniaxial pressure-induced half-metallic ferromagnetic phase transition inLaMnO3

Uniaxial pressure-induced half-metallic ferromagnetic phase transition inLaMnO3

Charge states and magnetic ordering in LaMnO3/SrTiO3superlattices

Topotactic Phase Transformation of the Brownmillerite SrCoO2.5 to the Perovskite SrCoO3–δ

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Topotactic Phase Transformation of the Brownmillerite SrCoO_2.5 to the Perovskite SrCoO_3–_δ