⇦Chinese Physics Letters, 2021, Vol. 38, No. 7, Article code 077103 Concurrent Structural and Electronic Phase Transitions in V$_2$O$_3$ Thin Films with Sharp Resistivity Change Chuang Xie (谢闯)1, Ling Hu (胡令)2*, Ran-Ran Zhang (张冉冉)3, Shun-Jin Zhu (朱顺进)2, Min Zhu (朱敏)2, Ren-Huai Wei (魏仁怀)2, Xian-Wu Tang (汤现武)2, Wen-Hai Song (宋文海)2, Xue-Bin Zhu (朱雪斌)2*, and Yu-Ping Sun (孙玉平)2,3,4* Affiliations 1Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China 2Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China 3High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China 4Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China Received 29 March 2021; accepted 8 May 2021; published online 3 July 2021 Supported by the National Key R&D Program of China (Grant No. 2017YFA0403600), and Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences Large-Scale Scientific Facility (Grant No. U1532149).
*Corresponding authors. Email: huling@issp.ac.cn; xbzhu@issp.ac.cn; ypsun@issp.ac.cn Citation Text: Xie C, Hu L, Zhang R R, Zhu S J, and Zhu M et al. 2021 Chin. Phys. Lett. 38 077103    Abstract The relationship between structural and electronic phase transitions in V$_2$O$_3$ thin films is of critical importance for understanding of the mechanism behind metal–insulator transition (MIT) and related technological applications. Despite being extensively studied, there are currently no clear consensus and picture of the relation between structural and electronic phase transitions so far. Using V$_2$O$_3$ thin films grown on $r$-plane Al$_2$O$_3$ substrates, which exhibit abrupt MIT and structural phase transition, we show that the electronic phase transition occurs concurrently with the structural phase transition as revealed by the electrical transport and Raman spectra measurements. Our result provides experimental evidence for clarifying this issue, which could form the basis of theoretical studies as well as technological applications in V$_2$O$_3$. DOI:10.1088/0256-307X/38/7/077103 © 2021 Chinese Physics Society Article Text Vanadium sesquioxide (V$_2$O$_3$) is an archetypical correlated oxide which exhibits a metal–insulator transition (MIT) accompanied by a structural phase transition (SPT) and a magnetic transition from a high-temperature paramagnetic metallic (PM) phase with a corundum structure to a low-temperature antiferromagnetic insulating (AFI) phase with a monoclinic structure around 160 K.[1] The entanglement of MIT with SPT and magnetic transition complicates the underlying physics and hinders a complete understanding of the MIT.[2–7] An important question is whether electronic correlation or structural effect accounts for the MIT in V$_2$O$_3$. Therefore, the clarification of the relation between SPT and MIT is a prerequisite to understand the mechanism behind these transitions. Despite decades of effort, clear consensus and a picture of the relation between SPT and MIT have not yet emerged.[1–10] Extended x-ray absorption fine structure (EXAFS) measurements have indicated that a continuous increase of the monoclinic distortion in the basal plane is observed far above the MIT.[2] Experimental evidence of the lattice precursor of the MIT has been revealed by surface acoustic waves in V$_2$O$_3$ thin films.[3] The MIT and SPT have been founded to decouple by a combining study of near-field infra-red (IR) imaging and x-ray diffraction (XRD) in V$_2$O$_3$ thin films.[4] In contrast, the MIT has been found to be tightly coupled to the SPT in V$_2$O$_3$ thin films by virtue of IR spectroscopy and XRD to determine electronic and structural phase fractions across the transition.[5] Furthermore, low-energy muon spin relaxation study has demonstrated that the magnetic transition occurs simultaneously with both MIT and SPT.[6] Especially, Raman spectroscopy is a quick, convenient, non-destructive, and non-invasive probe for characterizing the SPT.[8–18] However, the Raman spectroscopy in V$_2$O$_3$ gives rise to controversial results regarding to the relation between SPT and MIT.[8–10] The Raman spectra in the V$_2$O$_3$ single crystal corresponding to phonon and magnon excitations exhibits drastic changes across the MIT, indicating the intertwined electronic, structural, and magnetic transitions.[8,9] However, decoupling of the MIT and SPT with a temperature interval of $\sim $23 K has been observed in a V$_2$O$_3$ thin film grown on a Si substrate by combining temperature-dependent Raman spectra and resistivity measurements.[10] V$_2$O$_3$ thin films are sensitive to numerous factors such as strain states, substrate disorders, substrate orientations, and growth atmospheres, which account for the diverse electrical transport properties and much broadening MIT as compared to the bulk material.[10,19–25] The transition temperature of MIT ($T_{\rm MIT}$) derived from the resistivity derivatives with peak values in V$_2$O$_3$ thin films represents the formation or destruction of percolation conduction.[4,10,26] As a result, the $T_{\rm MIT}$ would be sensitive to the change of local conducting paths. In contrast, the Raman spectra is volume sensitive.[8–18] The degree of decoupling between SPT and MIT may be overestimated in V$_2$O$_3$ thin films with broadening MIT.[3–6,10] In this respect, the realization of sharp MIT in V$_2$O$_3$ thin films would be the precondition for clarifying this issue and technological applications as well.[5,6,26–28] A previous study has reported that V$_2$O$_3$ thin films grown on $r$-plane Al$_2$O$_3$ substrates are more prone to obtain sharp MIT than on the $c$-plane of Al$_2$O$_3$ substrates.[25] Furthermore, the variation of oxygen stoichiometry could strongly affect the electrical transport properties as well as MIT due to the multivalent nature of vanadium.[29–31] As a result, the MIT in V$_2$O$_3$ thin films would critically depend on the film growth conditions, which lead to the stabilization of specific vanadium oxides.[22,30,32–34] During growth of oxide films, the oxygen sources are the target, the background gas, and the substrate.[32,35,36] Therefore, precise control of growth atmosphere is vital to stabilize the +3 oxidation state of vanadium for the growth of V$_2$O$_3$ thin films when using either a metal target associated with oxidation or a V$_2$O$_5$ target associated with reduction.[22,30,37] In this respect, the V$_2$O$_3$ ceramic target may be a better choice for growth of stoichiometric V$_2$O$_3$ thin films.[19–21] The commonly used Al$_2$O$_3$ substrate can be regarded as having negligible oxygen contribution to the V$_2$O$_3$ thin film because of high formation energy of oxygen vacancy.[38] Based on the above considerations, we report the growth of V$_2$O$_3$ thin films on $r$-plane Al$_2$O$_3$ substrates by pulsed laser deposition (PLD) from a V$_2$O$_3$ ceramic target. Electrical transport measurements reveal that the V$_2$O$_3$ thin films deposited at substrate temperature ($T_{\rm S}$) of 773–923 K exhibit obvious MIT. In particular, the V$_2$O$_3$ thin film deposited at 923 K exhibits excellent MIT characteristics with sharp and large resistivity change. Raman spectroscopy investigation shows that the SPT related to the phonon modes of corundum and monoclinic structures occur concurrently with MIT. V$_2$O$_3$ thin films of $\sim $70 nm were grown on $r$-plane Al$_2$O$_3$ substrates by PLD. A KrF excimer laser with a repetition rate of 5 Hz and an energy density of 2 J/cm$^2$ was focused on a V$_2$O$_3$ ceramic target. During film growth, the $T_{\rm S}$ was varied in the range of 773–923 K and the oxygen partial pressure in the growth chamber was maintained at $\sim$$2\times 10^{-4}$ Pa. Structural properties of the V$_2$O$_3$ thin films were characterized by XRD using Cu $K_\alpha$ radiation at room temperature. The film thickness was determined to be $\sim $70 nm by a field emission scanning electron microscope (Fig. S1 in the Supplementary Material). The chemical component and valence states of the elements were evaluated by x-ray photoelectron spectroscopy (XPS) with monochromatic Al $K_\alpha$ ($h\nu = 1486.6$ eV). Binding energy data is referenced to the C $1s$ peak of 284.8 eV. Electrical transport properties were measured on a physics properties measurement system (PPMS) using the standard four-probe method setup. The Raman spectra measurements were performed from 25 K to 300 K by using a Horiba Jobin YvonT64000 Micro-Raman instrument with a torus 532 laser ($\lambda = 532$ nm) as an excitation source in a backscattering geometry. A back-illuminated charge coupled device (CCD) cooled by liquid nitrogen was used to detect the scattered light.
cpl-38-7-077103-fig1.png
Fig. 1. (a) XRD $\theta$–$2\theta$ profiles of V$_2$O$_3$ thin films grown on $r$-plane Al$_2$O$_3$ substrates at different $T_{\rm S}$. The inset shows the typical $\phi$ scan of the V$_2$O$_3$ thin film and Al$_2$O$_3$ substrate (006) reflections. (b) The change of $a$- and $c$-axis lattice parameters of V$_2$O$_3$ thin films with $T_{\rm S}$. The inset shows the variation of $c/a$ ratio with $T_{\rm S}$. The dashed line indicates the $c/a$ ratio of the V$_2$O$_3$ bulk material.
Figure 1(a) shows the XRD $\theta$–$2\theta$ profiles of the V$_2$O$_3$ thin films grown on the $r$-plane Al$_2$O$_3$ substrate at different $T_{\rm S}$. It is clear that the V$_2$O$_3$ thin films exhibit oriented growth along the Al$_2$O$_3$ substrates without any secondary phases. The inset of Fig. 1(a) depicts the typical $\phi$ scan of the V$_2$O$_3$ thin film and Al$_2$O$_3$ substrate (006) reflections, which indicates the epitaxial growth of V$_2$O$_3$ thin films on $r$-plane Al$_2$O$_3$ substrates. The high quality of the V$_2$O$_3$ thin films can also be attested by the rocking curve measurements ($\omega$-scan), exhibiting the full width at half maximum (FWHM) of 0.5$^{\circ}$–0.6$^{\circ}$ (Fig. S2 in the Supplementary Material). The ratio of the mean size of crystalline domains in the vertical direction increases and saturates to half of the thickness with increasing $T_{\rm S}$ (Fig. S3 in the Supplementary Material). The $c$ values of the V$_2$O$_3$ thin films were deduced from the (006) asymmetric reflections. The $a$ values of the V$_2$O$_3$ thin films were then determined from the interplanar spacing of the hexagonal based on the (102) reflections. As shown in Fig. 1(b), both $a$ and $c$ values of the V$_2$O$_3$ thin films weakly vary with increasing $T_{\rm S}$. Specifically, the $a$ ($c$) values decrease from 4.978 Å (14.033 Å) to 4.957 Å (13.984 Å) when the $T_{\rm S}$ is increased from 773 K to 923 K. As a consequence, $c/a$ ratios of the V$_2$O$_3$ thin films range from 2.819 to 2.825, which is very close to that of the bulk material.[8] A previous study has stated that $a$ values of V$_2$O$_3$ thin films grown on $r$-plane Al$_2$O$_3$ substrates close to the bulk value can be explained by considering the thermal expansion coefficient (TEC) of V$_2$O$_3$ and Al$_2$O$_3$.[25] The $a$-axis TEC of V$_2$O$_3$ and Al$_2$O$_3$ are $3.27 \times 10^{-5}$ K$^{-1}$ and $7.30 \times 10^{-6}$ K$^{-1}$, respectively.[39,40] The $a$-axis TEC mismatch between V$_2$O$_3$ and Al$_2$O$_3$ would expand the $a$-axis with increasing $T_{\rm S}$. Therefore, the narrow distributions of $a$, $c$, and $c/a$ values cannot be explained by the TEC mismatch and the reason needs further investigation.
cpl-38-7-077103-fig2.png
Fig. 2. (a) Typical XPS spectra for the V$_2$O$_3$ thin film of (a) wide scan and (b) V 2$p$ and O 1$s$ core levels.
XPS measurement has been performed to evaluate the chemical component and oxidation state of the V$_2$O$_3$ thin film. Figure 2(a) displays the typical wide scan spectrum of the V$_2$O$_3$ thin film. The elements V, O, and C can be clearly seen from the photoelectron peaks. The C $1s$ peak at 284.8 eV is taken as the binding energy reference. Figure 2(b) shows the spectra of the V 2$p$ and O 1$s$ core level, in which the dotted and solid lines represent the experimental data and fitting result. The fitting binding energies of V 2$p_{3/2}$ and V 2$p_{1/2}$ are 515.5 and 523.1 eV, which are consistent with the splitting of V 2$p$ level into V 2$p_{3/2}$ and V 2$p_{1/2}$ due to spin-orbital coupling with a separated binding energy of $\sim $7.6 eV. The corresponding line widths of full width at half maximum (FWHM) are 3.1 and 4.0 eV, respectively. These values are in good agreement with the previously reported values of +3 valence state in V$_2$O$_3$.[22,41,42] The O 1$s$ level can be fitting to two peaks centered at 530 and 531.3 eV, which correspond to the V–O bound and the physically absorbed oxygen at the film surface, respectively.[22]
cpl-38-7-077103-fig3.png
Fig. 3. (a) Temperature dependence of resistivity of V$_2$O$_3$ thin films grown on $r$-plane Al$_2$O$_3$ at different $T_{\rm S}$. The inset shows the differential curve of resistivity with respect to temperature for the V$_2$O$_3$ thin film ($T_{\rm S} = 923$ K). (b) The variation of transition temperature ($T_{\rm MIT}$) and resistivity change ($\rho_{_{\scriptstyle 100\,{\rm K}}} / \rho_{_{\scriptstyle 200\,{\rm K}}}$) of the PM-AFI transition with the $T_{\rm S}$.
Figure 3(a) shows the temperature-dependent resistivity for the V$_2$O$_3$ thin films deposited at different $T_{\rm S}$. All the V$_2$O$_3$ thin films exhibit first-order MIT with obvious hysteresis between cooling and warming processes. Sakai et al. have indicated that the clamping of the V$_2$O$_3$ lattice by the $r$-plane substrate has less impact on the MIT due to the lesser restriction on simultaneous expansion of the $a$-axis and shrinkage of $c$-axis transition.[25] Kalcheim et al. have shown that a self-induced strain in a geometrically confined V$_2$O$_3$ thin film grown on a $c$-plane Al$_2$O$_3$ substrate manipulates the MIT.[43] Therefore, the lattices and MIT of the V$_2$O$_3$ thin films grown on $r$-plane Al$_2$O$_3$ substrates would have less of an affect by the substrates, which correspond to narrowly distributed $c/a$ ratios [as shown in the inset of Fig. 1(b)]. This result can be understood by the scenario of trigonal distortion, in which the $c/a$ ratio quantifies the degree of trigonal distortion to directly determine the PM-AFI transition.[44,45] It is clear that the trigonal distortion of VO$_6$ octahedra along (within) $c$-axis ($ab$ plane) in the V$_2$O$_3$ thin films would be hardly affected when growing on the $r$-plane Al$_2$O$_3$ substrates. The MIT of V$_2$O$_3$ can be quantitatively characterized by the transition temperature ($T_{\rm MIT}$), transition sharpness ($\Delta T$), and resistivity change across the transition.[4,10,26] The $T_{\rm MIT}$ is usually defined as the temperature where the resistivity derivatives exhibit a peak value. At $T_{\rm MIT}$, the sharpest change of resistivity represents the formation or destruction of percolation conduction.[4,26] The $\Delta T$ can be defined by the FWHW of the resistivity derivatives. It is clear that the transition sharpness ($\Delta T$) of the V$_2$O$_3$ thin films can be remarkably enhanced (reduced) by increasing $T_{\rm S}$. As shown in the inset of Fig. 3(a), the V$_2$O$_3$ thin film deposited at 923 K has a $\Delta T$ of $\sim $10 K for both cooling and warming processes. Figure 3(b) depicts the variation of $T_{\rm MIT}$ and resistivity change across the transition ($\rho _{\rm 100\,K} / \rho _{\rm 200\,K}$) with the $T_{\rm S}$. The $T_{\rm MIT}$ exhibits slight increases towards V$_2$O$_3$ bulk materials with the increase of $T_{\rm S}$. Furthermore, the $\rho _{\rm 100\,K} / \rho _{\rm 200\,K}$ can be greatly improved more than $10^{5}$ when the $T_{\rm S}$ is increased to 923 K. Therefore, the V$_2$O$_3$ thin film deposited at 923 K exhibits excellent MIT characteristics, which provides a very good platform for investigating the relationship between SPT and electronic transition in the V$_2$O$_3$ thin film.
cpl-38-7-077103-fig4.png
Fig. 4. (a) Temperature-dependent Raman spectra of the V$_2$O$_3$ thin film ($T_{\rm S} = 923$ K) in the cooling process. (b) Raman shifts of the phonon modes as a function of temperature.
Figure 4(a) shows the temperature-dependent Raman spectra of the V$_2$O$_3$ thin film in the cooling process. The SPT occurs around the PM-AFI transition, which is clearly evident from the appearance of the phonon modes corresponding to the corundum and monoclinic structures (Fig. S4 in the Supplementary Material for the warming process). Figure 4(b) shows the Raman shift of phonon modes as a function of temperature. In the high temperature of V$_2$O$_3$, the corundum structure exhibits the symmetry of $R\overline{3}C$ space group and the $D_{3d}$ point group two Raman irreducible representations $A_{\rm 1g}$ and $E_{\rm g}$ modes.[46] At 300 K, the Raman peaks at $\sim $234 cm$^{-1}$ and $\sim $502 cm$^{-1}$ can be assigned to the $A_{\rm 1g}$ modes, while the Raman peak at $\sim $208 cm$^{-1}$ is of $E_{\rm g}$ mode (Fig.  S5 in the Supplementary Material). The $A_{\rm 1g}$ ($E_{\rm g}$) mode shifts to a high (low) frequency upon cooling from 300 K to 165 K (Fig. S6 in the Supplementary Material), which arises from the variation of the lattice structure.[1,47] In V$_2$O$_3$ with a corundum structure, the lattice vibrations related to $A_{\rm 1g}$ and $E_{\rm g}$ modes strongly depend on lattice parameters, interionic distances, and elastic constants $C_{\mu\nu}$.[45,47,48] The space group of the low-temperature monoclinic structure changes to $B2/b$ with the $C_{2\,h}$ point group, which has two groups of Raman active modes of $A_{g}$ and $B_{\rm g}$ modes.[47] The Raman peaks locate at $\sim $230 cm$^{-1}$, 278 cm$^{-1}$, 324 cm$^{-1}$, and 520 cm$^{-1}$ are of the $A_{\rm g}$ modes. The Raman locates at $\sim $192 cm$^{-1}$, $\sim $332 cm$^{-1}$, and $\sim $338 cm$^{-1}$ can be assigned to the $B_{\rm g}$ phonon modes. The Raman peak at $\sim $448 cm$^{-1}$ corresponds to a magnon scattering in the antiferromagnetic phase. It is clear that the corundum and monoclinic structures coexist in the hysteresis region at 165 K.
cpl-38-7-077103-fig5.png
Fig. 5. Normalized intensity of $A_{\rm g}$ phonon mode at $\sim $230 cm$^{-1}$, $\sim $278 cm$^{-1}$, and $\sim $324 cm$^{-1}$ in the V$_2$O$_3$ thin film versus temperature. The dotted lines are of guides for the eyes.
Figure 5 depicts the variation of the normalized intensity of the $A_{\rm g}$ phonon modes at $\sim $230 cm$^{-1}$, $\sim $278 cm$^{-1}$, and $\sim $324 cm$^{-1}$ with temperature, which is normalized to that at 50 K in the AFI phase with a monoclinic structure. The three Raman phonon modes are chosen because they are at the position where the strongest Raman peaks of the monoclinic structure are. In the high-temperature PM phase with a corundum structure, the normalized intensity of the $A_{\rm g}$ phonon modes is equal to zero. The monoclinic phase begins to nucleate and grow when decreasing temperature, which is evidenced by the appearance of the $A_{\rm g}$ phonon modes. The intensities of the $A_{\rm g}$ phonon modes increase rapidly and saturate with further decreasing temperature, which are in good agreement with the resistivity change across the MIT. The similar phenomenon is also observed in the warming process (Fig. S7 in the Supplementary Material). A previous study has shown that the growth of insulating (metallic) domains in an metallic (insulating) background on cooling (warming) in the percolation conduction of V$_2$O$_3$ thin film for the MIT tends to be along specific direction with respect to the Al$_2$O$_3$ substrate.[4] In contrast, the percolation conduction in the V$_2$O$_3$ thin film grown on the Si substrate may start with random growth of insulating (metallic) domains, which results in the lower $T_{\rm MIT}$ and broadening MIT. Therefore, the decoupling of SPT and MIT in the V$_2$O$_3$ thin film grown on a Si substrate may be extrinsic arising from the asynchronous contributions to electrical transport and Raman spectra by the coexistence and competition of the PM phase with a corundum structure and AFI phase with a monoclinic structure.[10] In our case, the growth of insulating (metallic) domains in the V$_2$O$_3$ thin film grown on an $r$-plane Al$_2$O$_3$ substrate could contribute to both electrical transport and Raman spectra in a synchronous manner, which results in the concurrent SPT and MIT. In summary, the V$_2$O$_3$ thin films have been grown on $r$-plane Al$_2$O$_3$ substrates by PLD from a V$_2$O$_3$ ceramic target. The V$_2$O$_3$ thin film deposited at 923 K exhibits excellent MIT characteristics including $\Delta T\sim 10$ K and $\rho _{\rm 100\,K} / \rho _{\rm 200\,K}\sim 10^{5}$. Furthermore, temperature-dependent electrical transport and Raman spectra measurements reveal that the SPT and MIT occur concurrently in the V$_2$O$_3$ thin film with sharp resistivity change. Our result provides experimental evidence for understanding the mechanism behind the MIT in V$_2$O$_3$. One can see the Supplementary Material for the cross-section SEM image, the rocking curve measurements ($\omega$-scan), the variation of mean size of the crystalline domains, the decomposition of $E_{\rm g}$ and $A_{\rm 1g}$ modes using Lorentzian fitting, the enlarged view of Raman spectra at different temperatures (300–165 K), the temperature-dependent Raman spectra of the V$_2$O$_3$ thin film ($T_{\rm S} = 923$ K) and the normalized intensity of the $A_{\rm g}$ phonon mode at $\sim $230 cm$^{-1}$, $\sim $278 cm$^{-1}$, and $\sim $324 cm$^{-1}$ in the warming process. References Metal-Insulator Transition in ( V 1 − x Cr x ) 2 O 3 Structural precursor to the metal-insulator transition in V 2 O 3 Direct observation of the lattice precursor of the metal-to-insulator transition in V 2 O 3 thin films by surface acoustic wavesNanotextured phase coexistence in the correlated insulator V2O3Robust Coupling between Structural and Electronic Transitions in a Mott MaterialIntertwined magnetic, structural, and electronic transitions in V 2 O 3 Mott-Hubbard transition in V 2 O 3 revisitedRaman scattering and phase transitions of V 2 O 3 Optical study of the Mott transition in V 2 O 3 : Comparison of time- and frequency-domain resultsStabilization of metallic phase in V 2 O 3 thin filmInfrared and Raman studies of the Verwey transition in magnetiteMechanism and observation of Mott transition in VO 2 -based two- and three-terminal devicesDirect Correlation of Structural Domain Formation with the Metal Insulator Transition in a VO 2 NanobeamPressure-Induced Metallization of Molybdenum DisulfideRaman spectroscopy of transition metal dichalcogenidesStructural phase transition in monolayer MoTe2 driven by electrostatic dopingIsostructural metal-insulator transition in VO 2Origin of the structural phase transition in single-crystal TaT e 2 Epitaxial strain effects on the metal–insulator transition in V2O3 thin filmsGrowth of V 2 O 3 thin films on a -plane (110) and c -plane (001) sapphire via pulsed-laser depositionThickness dependence of electronic phase transitions in epitaxial V2O3 films on (0001) LiTaO3Strain-induced pressure effect in pulsed laser deposited thin films of the strongly correlated oxide V 2 O 3 Substrate-induced disorder in V 2 O 3 thin films grown on annealed c -plane sapphire substratesEvidence of the metal-insulator transition in ultrathin unstrained V 2 O 3 thin filmsTransport properties and c/a ratio of V 2 O 3 thin films grown on C- and R-plane sapphire substrates by pulsed laser depositionGiant nonvolatile resistive switching in a Mott oxide and ferroelectric hybridNon-thermal resistive switching in Mott insulator nanowiresOxide Electronics Utilizing Ultrafast Metal-Insulator TransitionsPhase diagram and some physical properties of V2O3+x (0 ⩽ x ⩽ 0.080)Tuning metal-insulator transitions in epitaxial V 2 O 3 thin filmsEnhanced metal–insulator transition in V2O3 by thermal quenching after growthOxygen vacancies-induced metal-insulator transition in La2/3Sr1/3VO3 thin films: Role of the oxygen substrate-to-film transferGrowth control of the oxidation state in vanadium oxide thin filmsSharp contrast in the electrical and optical properties of vanadium Wadsley ( V m O 2 m + 1 , m > 1 ) epitaxial films selectively stabilized on (111)-oriented Y-stabilized Zr O 2 The origin of oxygen in oxide thin films: Role of the substrateSIMS of thin films grown by pulsed laser deposition on isotopically labeled substratesStrain-induced resistance change in V 2 O 3 films on piezoelectric ceramic disksTheoretical Formation Energy of Oxygen-Vacancies in OxidesThermal expansion of corundum structure Ti 2 O 3 and V 2 O 3Thermal expansion of AlN, sapphire, and siliconStoichiometric vanadium oxides studied by XPSRoom-temperature epitaxial growth of V2O3 filmsStructural Manipulation of Phase Transitions by Self‐Induced Strain in Geometrically Confined Thin FilmsSpectroscopy of metallic and insulating V 2 O 3 Unveiling the mechanisms of metal-insulator transitions in V 2 O 3 : The role of trigonal distortionSymmetry properties of the normal modes of vibration of calcite and α-corundumRaman scattering and phase transitions in V 2 O 3 and ( V 1 − x Cr x ) 2 O 3 Lattice-dynamical model for the elastic constants and Raman frequencies in ( V 1 − x Cr x ) 2 O 3
[1] McWhan D B and Remeika J P 1970 Phys. Rev. B 2 3734
[2] Pfalzer P, Obermeier G, Klemm M, Horn S, and denBoer M L 2006 Phys. Rev. B 73 144106
[3] Kündel J, Pontiller P, Müller C, Obermeier G, Liu Z, Nateprov A A, Hörner A, Wixforth A, Horn S, and Tidecks R 2013 Appl. Phys. Lett. 102 101904
[4] McLeod A S, Heumen E V, Ramirez J G, Wang S, Saerbeck T, Guenon S, Goldflam M, Anderegg L, Kelly P, Mueller A, Liu M K, Schuller I K, and Basov D N 2017 Nat. Phys. 13 80
[5] Kalcheim Y, Butakov N, Vargas N M, Lee M H, del V J, Trastoy J, Salev P, Schuller J, and Schuller I K 2019 Phys. Rev. Lett. 122 057601
[6] Frandsen B A, Kalcheim Y, Valmianski I, McLeod A S, Guguchia Z, Cheung S C, Hallas A M, Wilson M N, Cai Y, Luke G M, Salman Z, Suter A, Prokscha T, Murakami T, Kageyama H, Basov D N, Schuller I K, and Uemura Y J 2019 Phys. Rev. B 100 235136
[7] Hansmann P, Toschi A, Sangiovanni G, Saha-Dasgupta T, Lupi S, Marsi M, and Held K 2013 Phys. Status Solidi B 250 1251
[8] Kuroda N and Fan H Y 1977 Phys. Rev. B 16 5003
[9] Misochko O V, Tani M, Sakai K, Kisoda K, Nakashima S, Andreev V N, and Chudnovsky F A 1998 Phys. Rev. B 58 12789
[10] Majid S S, Shukla D K, Rahman F, Gautam K, Choudhary R J, Sathe V G, and Phase D M 2017 Appl. Phys. Lett. 110 173101
[11] Gasparov L V, Tanner D B, Romero D B, Berger H, Margaritondo G, and Forro L 2000 Phys. Rev. B 62 7939
[12] Kim H T, Chae B G, Youn D H, Maeng S L, Kim G, Kang K Y, and Lim Y S 2004 New J. Phys. 6 52
[13] Zhang S, Chou J Y, and Lauhon L J 2009 Nano Lett. 9 4527
[14] Chi Z H, Zhao X M, Zhang H, Goncharov A F, Lobanov S S, Kagayama T, Sakata M, and Chen X J 2014 Phys. Rev. Lett. 113 036802
[15] Saito R, Tatsumi Y, Huang S, Ling X, and Dresselhaus M S 2016 J. Phys.: Condens. Matter 28 353002
[16] Wang Y, Xiao J, Zhu H, Li Y, Alsaid Y, Fong K Y, Zhou Y, Wang S, Wu S, Wang Y, Zettl A, Reed E J, and Zhang X 2017 Nature 550 487
[17] Lee D, Chung B, Shi Y, Kim G Y, Campbell N, Xue F, Song K, Choi S Y, Podkaminer J, Kim T, Ryan P J, Kim J W, Paudel T R, Kang J H, Spinuzzi J W, Tenne D A, Tsymbal E Y, Rzchowski M S, Chen L Q, Lee J, and Eom C B 2018 Science 362 1037
[18] Gao J J, Si J G, Luo X, Yan J, Chen F C, Lin G T, Hu L, Zhang R R, Tong P, Song W H, Zhu X B, Lu W J, and Sun Y P 2018 Phys. Rev. B 98 224104
[19] Yonezawa S, Muraoka Y, Ueda Y, and Hiroi Z 2004 Solid State Commun. 129 245
[20] Allimi B S, Alpay S P, Goberman D, Huang T, Budnick J I, Pease D M, and Frenkel A I 2007 J. Mater. Res. 22 2825
[21] Allimi B S, Aindow M, and Alpay S P 2008 Appl. Phys. Lett. 93 112109
[22] Laurent S A, Mercey B, Chippaux D, Limelette P, and Ch S 2006 Phys. Rev. B 74 195109
[23] Brockman J, Samant M G, Roche K P, and Parkin S S 2012 Appl. Phys. Lett. 101 051606
[24] Dillemans L, Smets T, Lieten R R, Menghini M, Su C Y, and Locquet J P 2014 Appl. Phys. Lett. 104 071902
[25] Sakai J, Limelette P, and Funakubo H 2015 Appl. Phys. Lett. 107 241901
[26] Salev P, del V J, Kalcheim Y, and Schuller I K 2019 Proc. Natl. Acad. Sci. USA 116 8798
[27] Kalcheim Y, Camjayi A, del V J, Salev P, Rozenberg M, and Schuller I K 2020 Nat. Commun. 11 2985
[28] Yang Z, Ko C, and Ramanathan S 2011 Annu. Rev. Mater. Res. 41 337
[29] Ueda Y, Kosuge K, and Kachi S 1980 J. Solid State Chem. 31 171
[30] Thorsteinsson E B, Shayestehaminzadeh S, and Arnalds U B 2018 Appl. Phys. Lett. 112 161902
[31] Trastoy J, Kalcheim Y, del V J, Valmianski I, and Schuller I K 2018 J. Mater. Sci. 53 9131
[32] Hu L, Luo X, Zhang K J, Tang X W, Zu L, Kan X C, Chen L, Zhu X B, Song W H, Dai J M, and Sun Y P 2014 Appl. Phys. Lett. 105 111607
[33] Lee S, Meyer T L, Park S, Egami T, and Lee H N 2014 Appl. Phys. Lett. 105 223515
[34] Choi S, Son J, Oh J, Lee J, Jang J H, and Lee S 2019 Phys. Rev. Mater. 3 063401
[35] Schneider C W, Esposito M, Marozau I, Conder K, Doebeli M, Hu Y, Mallepell M, Wokaun A, and Lippert T 2010 Appl. Phys. Lett. 97 192107
[36] Stender D, Cook S, Kilner J A, Döbeli M, Conder K, Lippert T, and Wokaun A 2013 Solid State Ionics 249 56
[37] Sakai J, Bavencoffe M, Negulescu B, Limelette P, Wolfman J, Tateyama A, and Funakubo H 2019 J. Appl. Phys. 125 115102
[38] Tanaka I, Oba F, Tatsumi K, Kunisu M, Nakano M, and Adachi H 2002 Mater. Trans. 43 1426
[39] Eckert L J and Bradt R C 1973 J. Appl. Phys. 44 3470
[40] Yim W M and Paff R J 1974 J. Appl. Phys. 45 1456
[41] Hryha E, Rutqvist E, and Nyborg L 2012 Surf. Interface Anal. 44 1022
[42] Liu X B, Lu H B, He M, Jin K J, and Yang G Z 2014 Sci. Chin. Phys. Mech. & Astron. 57 1866
[43] Kalcheim Y, Adda C, Salev P, Lee M, Ghazikhanian N, Vargas N M, del V J, and Schuller I K 2020 Adv. Funct. Mater. 30 202005939
[44] Muller O, Urbach J P, Goering E, Weber T, Barth R, Schuler H, Klemm M, Horn S, and denBoer M L 1997 Phys. Rev. B 56 15056
[45] Hu L, Xie C, Zhu S J, Zhu M, Wei R H, Tang X W, Lu W J, Song W H, Dai J M, Zhang R R, Zhang C J, Zhu X B, and Sun Y P 2021 Phys. Rev. B 103 085119
[46] Cowley E R 1969 Can. J. Phys. 47 1381
[47] Tatsuyama C and Fan H Y 1980 Phys. Rev. B 21 2977
[48] Yang H and Sladek R J 1985 Phys. Rev. B 32 6634