Increased metal-insulator transition temperatures in epitaxial thin films of V2O3 prepared in reduced oxygen environments

Brockman, J.; Aetukuri, Nagaphani; Topuria, Teya; Samant, Mahesh G.; Roche, K. P.; Parkin, S. S. P.

doi:10.1063/1.3574910

Cited by 44 publications

(39 citation statements)

References 20 publications

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“…The MIT in V 2 O 3 has been studied in vacuum as a function of temperature and applied voltage both in bulk and in thin films 2,[9][10][11][12] . Furthermore , the pressure dependence of MIT has been studied in bulk in the (V 1-x Cr x ) 2 O 3 system [13][14][15] .…”

Section: Introductionmentioning

confidence: 99%

Deviation from bulk in the pressure-temperature phase diagram of V2O3 thin films

et al. 2017

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We found atypical pressure dependence in the transport measurements of the metal to insulator transition (MIT) in epitaxial thin films of vanadium sesquioxide (V 2 O 3). Three different crystallographic orientations and four thicknesses, ranging from 40 nm to 500 nm, were examined under hydrostatic pressures (P h) of up to 1.5 GPa. All of the films at transition exhibited a four order of magnitude resistance change with transition temperatures ranging from 140 K to 165 K depending on the orientation. This allowed us to build pressure-temperature phase diagrams several orientations and film thicknesses. Interestingly, for pressures below 500 MPa, all samples deviate from bulk behavior and show a weak transition temperature (T c) pressure dependence (dT c /dP h = 1.2x10-2 ±0.3x10-2 K/MPa), which recovers to bulk-like behavior (3.9x10-2 ±0.3x10-2 K/MPa) at higher pressures. Furthermore, we found that pressurization leads to morphological but not structural changes in the films. This indicates that the difference in the thin film and bulk pressure-temperature phase diagrams is most probably due to pressureinduced grain boundary relaxation as well as both plastic and elastic deformations in film microstructure. These results highlight the difference between bulk and thin films behaviors.

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Section: Introductionmentioning

confidence: 99%

Deviation from bulk in the pressure-temperature phase diagram of V2O3 thin films

et al. 2017

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“…The stabilizing effect of the substrate is particularly important for oxides that can occur in different oxidation states and structures. For instance, V2O3 is grown successfully on c-cut sapphire if the growth conditions, in particular oxygen background pressure and temperature, during growth are chosen appropriately [10,11,12,13,14,15,16]. On the other hand, to our knowledge, corundum Ti2O3 has not been successfully grown in a good quality epitaxial film on sapphire, likely because of its preference to form Ti 4+ .…”

Section: Introductionmentioning

confidence: 99%

Epitaxial corundum-VTiO3 thin films grown on c-cut sapphire

Sutter

Batzill

2017

Thin Solid Films

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Corundum structured VTiO3 has been grown as epitaxial films on c-cut sapphire by laser molecular beam epitaxy. The properties of the film were characterized by reflection high energy electron diffraction, x-ray diffraction, transmission electron microscopy (TEM), and photoemission spectroscopy. All the structural probes clearly indicate the corundum structure of the film. X-ray photoemission spectroscopy (XPS) indicates that V is in a 3+ charge state implying that Ti also should adopt a 3+ charge state in order for the corundum structure to form. However, the Ti-2p XPS, while clearly broadened to the lower binding energy side compared to TiO2, also exhibits a pronounced Ti 4+ component. Similarly TEMelectron energy loss spectroscopy indicates a mixture of Ti 3+ and Ti 4+. This is tentatively assigned to a combination of final state effects in XPS measurements and existence of excess (interstitial) oxygen. The valence band spectra show occupation of 3d metal states that resemble more closely those of Ti2O3 than for V2O3, suggesting that mostly the a1g molecular states are occupied.

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“…Upon cooling below ~ 150-160 K this material demonstrates a fascinating 'insulator-metal'-type transition with simultaneous jump in electrical resistivity by several orders of magnitude and monoclinic distortion of the crystal structure [10][11][12][13][14][15][16][17][18]. Because of scientific and technologic importance, this characteristic transition was the main focus of studies of V 2 O 3 during several decades [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Anomalous compression and new high-pressure phases of vanadium sesquioxide, V₂O₃

Ovsyannikov¹,

Trots²,

Kurnosov³

et al. 2013

J. Phys.: Condens. Matter

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We report results of a powder x-ray diffraction (XRD) study of vanadium sesquioxide, V2O3, under pressurization in a neon pressure-transmitting medium up to 57 GPa. We have established a bulk modulus value for corundum-type V2O3 of B0 = 150 GPa at B' = 4. This bulk modulus value is the lowest among those known for the corundum-type-structured oxides, e.g. Al2O3, α-Fe2O3, Cr2O3, Ti2O3, and α-Ga2O3. We have proposed that this might be related to the difference in the electronic band structures: at room temperature V2O3 is metallic, but the above corundum-structured sesquioxides are semiconducting or insulating. Around ∼21-27 and ∼50 GPa we registered changes in the XRD patterns that might be addressed to phase transitions. These transitions were sluggish upon room-temperature compression, and hence we additionally facilitated them by the laser heating of one sample. We have refined the XRD patterns of only the first high-pressure phase in an orthorhombic lattice of a Rh2O3(II)-type. Our findings significantly extend the knowledge of the P-T phase diagram of V2O3 and advance the understanding of its properties. We speculate that the elastic properties of V2O3 can be closely linked to its electronic band structure and, consequently, we propose that slightly doped V2O3 (e.g. with Cr) could be a potential candidate for systems in which the bulk modulus value may be remarkably switched by moderate pressure or temperature.

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Increased metal-insulator transition temperatures in epitaxial thin films of V2O3 prepared in reduced oxygen environments

Cited by 44 publications

References 20 publications

Deviation from bulk in the pressure-temperature phase diagram of V2O3 thin films

Deviation from bulk in the pressure-temperature phase diagram of V2O3 thin films

Epitaxial corundum-VTiO3 thin films grown on c-cut sapphire

Anomalous compression and new high-pressure phases of vanadium sesquioxide, V₂O₃

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Increased metal-insulator transition temperatures in epitaxial thin films of V2O3 prepared in reduced oxygen environments

Cited by 44 publications

References 20 publications

Deviation from bulk in the pressure-temperature phase diagram of V2O3 thin films

Deviation from bulk in the pressure-temperature phase diagram of V2O3 thin films

Epitaxial corundum-VTiO3 thin films grown on c-cut sapphire

Anomalous compression and new high-pressure phases of vanadium sesquioxide, V2O3

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Anomalous compression and new high-pressure phases of vanadium sesquioxide, V₂O₃