Growth and epitaxial structure of LaVOx films

Hotta, Yoshiki; Mukunoki, Yasushige; Susaki, Tomofumi; Hwang, Harold Y.; Fitting, Lena; Muller, David A.

doi:10.1063/1.2227786

Cited by 45 publications

(37 citation statements)

References 13 publications

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“…The growth temperature was 600°C and the oxygen partial pressure was 1.0ϫ 10 −6 Torr for all processes. These conditions follow our previous optimization of high-quality LaVO 3 thin-film growth in the layer-by-layer growth mode 19 with one exception. Note the different laser conditions: we now use a four lens afocal zoom stage to accurately image an aperture rather than a single lens just off of the focusing condition.…”

Section: Methodsmentioning

confidence: 84%

Modulation doping of a Mott quantum well by a proximate polar discontinuity

et al. 2009

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We present evidence for hole injection into LaAlO 3 / LaVO 3 / LaAlO 3 quantum wells near a polar surface of LaAlO 3 ͑001͒. As the surface is brought in proximity to the LaVO 3 layer, an exponential drop in resistance and a decreasing positive Seebeck coefficient are observed below a characteristic coupling length of 10-15 unit cells. We attribute this behavior to a crossover from an atomic reconstruction of the AlO 2 -terminated LaAlO 3 surface to an electronic reconstruction of the vanadium valence. These results suggest a general approach to tunable hole doping in oxide thin-film heterostructures.

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Section: Methodsmentioning

confidence: 84%

Modulation doping of a Mott quantum well by a proximate polar discontinuity

et al. 2009

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“…3 Particular interest in epitaxial LaVO 3 films has been driven by the "polar discontinuity" at the interface LaVO 3 /SrTiO 3 , analogues to the LaAlO 3 /SrTiO 3 case. 4,5 The fabrication of phase pure LaVO 3 films, however, requires oxygen pressures lower than about 10 −5 mbar, so that the competing LaVO 4 phase does not form. The fabrication of the LaVO x films under high vacuum conditions affects the stoichiometry of the film and oxygen content of the SrTiO 3 substrates.…”

Section: +mentioning

confidence: 99%

“…22 The stabilization of the perovskite LaVO 3 phase in thin films was successful by performing the growth in either high vacuum 4,5,[7][8][9]22 or in pure Ar or Ar/H 2 atmosphere. 9,21 We fabricated the films by PLD using a KrF excimer laser.…”

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Probing orbital ordering in LaVO3 epitaxial films by Raman scattering

et al. 2016

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Single crystals of Mott-Hubbard insulator LaVO3 exhibit spin and orbital ordering along with a structural change below ≈140 K. The occurrence of orbital ordering in epitaxial LaVO3 films has, however, been little investigated. By temperature-dependent Raman scattering spectroscopy, we probed and evidenced the transition to orbital ordering in epitaxial LaVO3 film samples fabricated by pulsed-laser deposition. This opens up the possibility to explore the influence of different epitaxial strain (compressive vs. tensile) and of epitaxy-induced distortions of oxygen octahedra on the orbital ordering, in epitaxial perovskite vanadate films.

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“…[10,11] Unfortunately, these growth conditions are incompatible with many low oxidation state perovskites, which cannot maintain their structure above P O2 $ 10 À5 Torr. [12,13] To address this issue, we have attempted to understand the fundamental thermodynamic limitations of manganite thin film growth. We find that the oxygen vacancies observed previously arise from kinetic limitations, and that stoichiometric films with bulklike Curie temperatures (T c ) can be grown down to 10 À6 Torr, greatly expanding the range of materials compatibility.…”

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Enhanced Thermodynamic Stability of Epitaxial Oxide Thin Films

2008

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Given the diverse physical properties of closely latticematched perovskite oxides, these materials have the potential to form a heteroepitaxial family analogous to compound semiconductors, coupling many different degrees of freedom. [1,2] However, a potential limitation is the fact that various perovskites require vastly different thermodynamic conditions for bulk synthesis, ranging from strongly reducing to strongly oxidizing. This would appear to limit the range of materials that can be simultaneously stabilized in thin-film heterostructures. Here, we examine the growth phase diagram of La 0.7 Sr 0.3 MnO 3 thin films grown by pulsed laser deposition (PLD), which have been heavily studied for their magnetoresistive properties. Unlike previous reports, we obtain stoichiometric films as-grown, despite extremely reducing growth conditions, with bulklike Curie temperatures exceeding 360 K. Masking this stability is a particularly strong dependence of film stoichiometry on the laser profile at the target and the resulting kinetics of the ablated species on the film surface. These results indicate that bulk thermodynamic limitations can be overcome in perovskite films by PLD. After the successful demonstration to grow high-temperature superconductor films, [3] PLD has attracted wide interest and emerged as an important technique for fabricating crystalline oxide thin films with high epitaxial quality. Recently, artificial perovskite structures with atomic-scale variations have been grown by PLD in superlattices between LaFeO 3 /LaCrO 3 , LaMnO 3 /SrMnO 3 , and LaTiO 3 /SrTiO 3 , for example. [4][5][6] Several of these examples confront the need to (meta)stabilize different oxidation states of the same transition metal ion in the same structure, and growth is often a compromise between the ideal growth conditions for each constituent. More generally, it is desirable to stabilize complex heterostructures by using components with very different bulk thermodynamics. Epitaxial stabilization is a key concept for this purpose, and it has been used in a wide range of materials in thin-film form.[7]For this study we focus on perovskite manganites, which have already been widely used to incorporate colossal magnetoresistance and half-metallic ferromagnetism in heterostructures. For examples such as YBa 2 Cu 3 O 7 / La 2/3 Ca 1/3 MnO 3 interfaces, both constituents can be grown in highly oxidizing conditions with little compromise.[8] Thus far, however, manganites have been thought to be incompatible with reducing conditions. In the vast literature on manganite thin films, the growth conditions can be summarized in two categories: growth in an oxygen partial pressure (P O2 ) above 200 mTorr (1 Torr ¼ 1.333 Â 10 2 Pa), with or without post-annealing, [9] or growth in low P O2 $ 1 mTorr (or equivalent ozone, N 2 O, NO 2 pressure) which results in (La,A)MnO 3-d (A ¼ Sr, Ca, Ba, etc.) films, followed by post-annealing to recover oxygen stoichiometry. [10,11] Unfortunately, these growth conditions are incompatible with many low oxida...

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Growth and epitaxial structure of LaVOx films

Cited by 45 publications

References 13 publications

Modulation doping of a Mott quantum well by a proximate polar discontinuity

Modulation doping of a Mott quantum well by a proximate polar discontinuity

Probing orbital ordering in LaVO3 epitaxial films by Raman scattering

Enhanced Thermodynamic Stability of Epitaxial Oxide Thin Films

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