Effect of vanadium deficiency on properties of polycrystalline LaVO3

Gharetape, S. Jamali; Singh, M.; Razavi, F. S.; Crandles, D. A.; Zhao, Lianming; Leung, Kevin

doi:10.1063/1.3549179

Cited by 18 publications

(9 citation statements)

References 25 publications

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“…mately 1% greater than for the V-rich films. Such a difference is subtle but consistent, and in agreement with previous studies on the non-stoichiometric bulk LVO samples 38,39 .…”

Section: A Morphology and Structuresupporting

confidence: 92%

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Growth and Characterization of Off-Stoichiometric LaVO$_3$ Thin Films

Zhang,

Xin,

Karapetrova

et al. 2021

Preprint

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LaVO 3 (LVO) has been proposed as a promising material for photovoltaics because its strongly correlated d electrons can facilitate the creation of multiple electron-hole pairs per incoming photon, which would lead to increased device efficiency. In this study, we intentionally grow off-stoichiometric LVO films by changing the growth conditions such as laser fluence. Our aim is to study how deviating La:V stoichiometries affect the electronic properties of LVO thin films. We find that the off-stoichiometry clearly alters the physical properties of the films. Structural characterization shows that both La-rich and V-rich films have different levels of structural distortion, with La-rich (V-rich) films showing a larger (smaller) out-of-plane lattice parameter compared to what one would expect from epitaxial strain effects alone. Both types of films show deviation from the behavior of bulk LVO in optical measurement, i.e., they do not show signatures of the expected long range orbital order, which can be a result of the structural distortions or the presence of structural domains. In transport measurements, La-rich films display clear signatures of electronic phase separation accompanying a temperature induced metal-insulator transition, while V-rich films behave as Mott insulators. The out-of-plane lattice parameter plays a crucial role in determining the transport properties, as the crossover from Mott-insulating to disorder-induced phase-separated behavior occurs around a lattice parameter value of 3.96 Å, quite different from what has been previously reported.

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“…mately 1% greater than for the V-rich films. Such a difference is subtle but consistent, and in agreement with previous studies on the non-stoichiometric bulk LVO samples 38,39 .…”

Section: A Morphology and Structuresupporting

confidence: 92%

“…It is also possible that the extension of the out-of-plane direction plays a role in suppressing the formation of orbital order. The excess or deficiency of the vanadium alters the V-O-V bond lengths and angles 38,39 , leading to a more distorted bonding scheme possibly disrupting orbital ordering.…”

Section: B Absorptionmentioning

confidence: 99%

Growth and Characterization of Off-Stoichiometric LaVO$_3$ Thin Films

Zhang,

Xin,

Karapetrova

et al. 2021

Preprint

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“…Small deviation from perfect La/V ratio can be favored by oxygen deficiency in LVO 31,50 . However, such non-stoichiometry has only a small effect on the transport properties of LVO which is a robust semiconductor with only small band gap changes 33 . On the contrary, it is well known that STO becomes conducting even with a tiny doping by oxygen vacancies 8,10 .…”

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confidence: 99%

“…The sheet resistance R s of the films was measured as a function of the temperature T (See Fig.2). LVO is a localized system with semiconducting conductivity 31 even in the presence of some cationic and/or oxygen vacancies 32,33 while pure stoichiometric STO is insulating. However, a clear metallic behavior with (dR/dT)>0 is clearly observed up to a temperature T * .…”

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confidence: 99%

Two components for one resistivity in LaVO₃/SrTiO₃heterostructure

Rotella¹,

Copie²,

Pautrat³

et al. 2015

J. Phys.: Condens. Matter

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A series of 100 nm LaVO3 thin films have been synthesized on (001)-oriented SrTiO3 substrates using the pulsed laser deposition technique, and the effects of growth temperature are analyzed. Transport properties reveal a large electronic mobility and a non-linear Hall effect at low temperature. In addition, a cross-over from a semiconducting state at high-temperature to a metallic state at low-temperature is observed, with a clear enhancement of the metallic character as the growth temperature increases. Optical absorption measurements combined with the two-bands analysis of the Hall effect show that the metallicity is induced by the diffusion of oxygen vacancies in the SrTiO3 substrate. These results allow to understand that the film/substrate heterostructure behaves as an original semiconducting-metallic parallel resistor, and electronic transport properties are consistently explained. The discovery of unexpected conducting or superconducting behaviors when stacking two band insulators like LaAlO 3 (LAO) and SrTiO 3 (STO) has motivated intense activities to understand these phenomena [1][2][3] . The origin of the highly mobile charge carriers appears the central point of the debate. Interpretations are based on an electronic reconstruction at the interface due to a polar discontinuity between the two insulators 2-5, on cation intermixing or on oxygen vacancies [6][7][8] . It has also been shown that 2D electronic conduction can be observed for peculiar controlled conditions. In particular, the oxygen pressure used during the film growth and the annealing conditions are critical parameters. They allow to tune the amount of oxygen vacancies and the dimensionality of transport properties 9,10 . Using a Mott insulator having a strong coulomb interaction instead of a band insulator should allow to take advantage of the rich properties of electronic correlated systems 11, and other systems such as LaTiO 3 /SrTiO 3 (LTO/STO) have been investigated 12,13 . Similarly to LAO/STO, LTO/STO displays a conducting behavior which was explained by an electronic reconstruction, and superconductivity emerges at low temperature 13. LaVO 3 /SrTiO 3 (LVO/STO) is another interesting oxide heterostructure, LVO being a Mott insulator that exhibits an antiferromagnetic spin order 14. Besides the existence of a 2D electron gaz proposed at the LVO/STO interface 15, new phenomena could arise from the combination of confined carriers at the interface and strong correlations in LVO. Thin films of LVO/STO were synthesized using the pulsed laser deposition (PLD) technique by Hotta et al. 16. Importantly, a pure LVO phase can be formed only under low partial pressure of oxygen (typ. < 10Torr), and a postannealing under oxygen should be avoided since the oxidized form of LaVO 4 is quickly stabilized. Therefore, the problematic of oxygen vacancies is specially relevant for LVO/STO. Regarding the physical properties, this heterostructure presents a conducting behavior and a low temperature non linear Hall effect, both explained by the intrinsic m...

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“…To overcome these limitations, one possibility is to tune the carrier concentration of such materials. There are several possibilities to do this such as varying the La/V ratios and oxygen stoichiometry, and introducing additional substituents for La or V. Indeed, it was shown that V is present in 3+ and 4+ valence (Gharetape et al, 2011).…”

Section: State Of the Artmentioning

confidence: 99%