Mesoscopic electronic heterogeneities in the transport properties of V<sub>2</sub>O<sub>3</sub>thin films

Grygiel, C.; Pautrat, Alain; Sheets, William C.; Prellier, W.; Mercey, B.; Méchin, Laurence

doi:10.1088/0953-8984/20/47/472205

Cited by 14 publications

(19 citation statements)

References 23 publications

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“…One assumption is that the conducting thickness of the STO is fixed by the diffusion length of oxygen vacancies at the macroscopic scale, and could be strongly dependent on the growth temperature. Note this parallel resistor with opposite temperature variation mimics an equivalent resistor with non-monotonic temperature variation which presents a resistance maximum at some intermediate temperature 51 , in qualitative agreement with our measurements (Fig.2). To be more quantitative, G i , ρ i and t i will stand for conductance, resistivity and thickness, respectively, while i=1,2 are the LVO and STO.…”

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confidence: 90%

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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supporting

confidence: 90%

Two components for one resistivity in LaVO₃/SrTiO₃heterostructure

Rotella¹,

Copie²,

Pautrat³

et al. 2015

J. Phys.: Condens. Matter

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“…The temperature-resistance characteristic of these films is another parameter useful to evaluate the film quality, and the normalization of the resistance variation can be used for observing the multiple transitions. 43 The ratios of the electrical resistance at 35 and 85…”

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Spectroscopic analysis of phase constitution of high quality VO2 thin film prepared by facile sol-gel method

Fan

Chen

et al. 2013

AIP Advances

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VO2 thin films with large-area were prepared on Al2O3 substrates by a simple sol-gel method. After an annealing treatment under low vacuum condition, all the VO2 films showed a preferred growth direction and exhibited excellent semiconductor-metal transition (SMT) characteristics. The structure and electrical properties of the obtained VO2 films were investigated systematically. Raman spectra, X-ray diffraction and X-ray absorption spectra measurements pointed out that the VO2 film on ${\rm A}{\rm l}_{\rm 2} {\rm O}_{\rm 3} ( {{\rm 10}\overline {\rm 1} {\rm 0}})$Al2O3(101¯0) substrate showed a M1 phase instead of M2 phase as reported in previous studies. Based on the experiment results, it was suggested that the strained structure of oriented VO2 films could be a mechanism for the formation of the intermediate M2 phase, whereas it is difficult to access the pure M2 phase of undoped VO2 films. VO2 film on ${\rm A}{\rm l}_{\rm 2} {\rm O}_{\rm 3} \left( {{\rm 10}\overline {\rm 1} {\rm 0}} \right)$Al2O3101¯0 substrate showed a lower SMT temperature compared to VO2 film on Al2O3 (0001), which can be mostly attributed to the differences of both lattice mismatch and thermal stress. The present results confirm and make clear the relevance of the substrate orientation in the growth of VO2 film and their different contributions to the SMT characteristics in vanadate systems.

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“…Furthermore, a number of authors report the absence or a significant attenuation of the MIT in ultrathin layers. [10][11][12] In this work, we investigate the influence of a Cr 2 O 3 buffer layer and the V 2 O 3 thickness on the transport properties. We demonstrate a MIT in ultrathin V 2 O 3 layers down to 3.…”

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confidence: 99%

“…15 Most of the V 2 O 3 thin film work reported in the literature involves the epitaxial deposition of V 2 O 3 on substrates that have a rather large misfit with V 2 O 3 . 3,[10][11][12][13][16][17][18][19][20] In particular, (0001)-oriented Al 2 O 3 with hexagonal unit cell spacings of a ¼ 4.754 Å and c ¼ 12.975 Å is often used as a substrate. Bulk V 2 O 3 has lattice spacings of a ¼ 4.954 Å and c ¼ 14.008 Å .…”

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Evidence of the metal-insulator transition in ultrathin unstrained V2O3 thin films

Dillemans¹,

Smets²,

Lieten³

et al. 2014

Applied Physics Letters

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We report the strain state and transport properties of V 2 O 3 layers and V 2 O 3 /Cr 2 O 3 bilayers deposited by molecular beam epitaxy on (0001)-Al 2 O 3 . By changing the layer on top of which V 2 O 3 is grown, we change the lattice parameters of ultrathin V 2 O 3 films significantly. We find that the metal-insulator transition is strongly attenuated in ultrathin V 2 O 3 layers grown coherently on Al 2 O 3 . This is in contrast with ultrathin V 2 O 3 layers grown on Cr 2 O 3 buffer layers, where the metal-insulator transition is preserved. Our results provide evidence that the existence of the transition in ultrathin films is closely linked with the lattice deformation. V

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Mesoscopic electronic heterogeneities in the transport properties of V₂O₃thin films

Cited by 14 publications

References 23 publications

Two components for one resistivity in LaVO₃/SrTiO₃heterostructure

Two components for one resistivity in LaVO₃/SrTiO₃heterostructure

Spectroscopic analysis of phase constitution of high quality VO2 thin film prepared by facile sol-gel method

Evidence of the metal-insulator transition in ultrathin unstrained V2O3 thin films

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Mesoscopic electronic heterogeneities in the transport properties of V2O3thin films

Cited by 14 publications

References 23 publications

Two components for one resistivity in LaVO3/SrTiO3heterostructure

Two components for one resistivity in LaVO3/SrTiO3heterostructure

Spectroscopic analysis of phase constitution of high quality VO2 thin film prepared by facile sol-gel method

Evidence of the metal-insulator transition in ultrathin unstrained V2O3 thin films

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Mesoscopic electronic heterogeneities in the transport properties of V₂O₃thin films

Two components for one resistivity in LaVO₃/SrTiO₃heterostructure

Two components for one resistivity in LaVO₃/SrTiO₃heterostructure