Direct observation of giant metallic domain evolution driven by electric bias in VO2 thin films on TiO2(001) substrate

Kanki, Teruo; Kawatani, Kenichi; Takami, Hidefumi; Tanaka, Hidekazu

doi:10.1063/1.4772211

Cited by 33 publications

(43 citation statements)

References 28 publications

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“…In this system, the metallic and insulating domains often coexist randomly around the transition temperature, and each domain works as an essential element invoking first order MIT [1][2][3] and influences the macroscopic transport property. The domain size ranges from several tens of nanometers [4][5][6] to the micrometer scale [7][8][9][10][11]. Recent reports have revealed that, in oxide materials with mixed domains, the elastic strain caused by lattice distortion or mismatch between the substrate and thin film can greatly impact their domain characteristics and electronic properties [7,[12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…In VO 2 thin films on rutile TiO 2 (001) substrates, strain caused by lattice mismatch between the film and substrate can shift T MI from 340 K to ß300 K [13,14]. Recently, in the VO 2 /TiO 2 (001) system we have observed the presence of giant microscale metallic domains with rectangular shapes and the first order transition induced within individual domains [2,[9][10][11]. Optical microscopy has been used to identify how the transport properties are changed by the MIT of each domain, supporting the relationship between the domain configurations and their electronic properties [2,[9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, in the VO 2 /TiO 2 (001) system we have observed the presence of giant microscale metallic domains with rectangular shapes and the first order transition induced within individual domains [2,[9][10][11]. Optical microscopy has been used to identify how the transport properties are changed by the MIT of each domain, supporting the relationship between the domain configurations and their electronic properties [2,[9][10][11]. Moreover, we showed that changing the size and aspect ratio of VO 2 thin films on TiO 2 (001) in relation to the domain configuration can significantly modulate transport properties [11].…”

Section: Introductionmentioning

confidence: 99%

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Formation mechanism of a microscale domain and effect on transport properties in strainedVO2thin films onTiO2(001)

2014

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We investigated film thickness dependence of domain size and transport property in VO 2 thin films on rutile TiO 2 (001) substrates and identified formation mechanism of the microscaled domain. It was found that domain size decreased with increasing film thickness and the domain boundary consisted of cracks and dislocations, clarified by high-resolution transmission electron microscopy. The detailed images showed, the tensile-strained VO 2 lattices received by TiO 2 (001) were partially relaxed around the cracks and dislocations. The relaxed lattice is likely to return the original metal-insulator transition temperature of 340 K, whereas the tensile-strained lattice has the transition at 300 K in a VO 2 /TiO 2 (001) system. Thus, the mixed states of strained and relaxed crystal lattice and the increase in dislocation density in thicker films cause the overly broad resistance behavior against temperature. Furthermore, the origin of the dislocations and the thickness dependence of the domain size could be explained by the energy release of shear stress generated by competition between the pinning layers at near-interface VO 2 layers holding the tetragonal structure and the near-surface layers separated from the substrate attempting the lattice transformation to a monoclinic structure. This understanding enables us to more precisely design the size and configuration of these domains and their transport properties.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Formation mechanism of a microscale domain and effect on transport properties in strainedVO2thin films onTiO2(001)

2014

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“…45 It is reported that electropulsing causes sudden reduction of electrical resistance and change of atomic element distribution in packed oxide powders. 46 The observed change of electrical resistance proves not to be due to thermal effects but is rather dominated by field induced dielectric breakdown. The current induced element reconfiguration has not been fully understood.…”

Section: Unclarified Effects Of Electropulsingmentioning

confidence: 99%

Critical Assessment 8: Outstanding issues in electropulsing processing

Qin

2015

Materials Science and Technology

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The processing of materials using electrical pulses utilises effects other than resistive heating to stimulate changes in their microstructure and hence the properties. The direct effect of electropulsing has not, however, been fully understood. There remain issues that delay the industrialisation of the method and there are gaps in the scientific understanding of mechanisms. The thermodynamic description of electropulsing is based on a few oversimplified geometric models. The corresponding kinetic description remains qualitative and less than helpful in stimulating applications. The role of electropulsing in multiphase materials where the magnetic permeabilities of the phases are different has not been explored. Experiments on electropulse induced powder sintering reveal effects that are not related to resistive heating, but their origin has yet to be identified. Similar uncertainties apply to the mechanisms for electrically induced crystal rotation and texture evolution. Electropulse induced particle reconfiguration in liquid suspensions is a new field that is promising in helping to clean melts from insulating oxides. These, and other aspects connected with applications and scaling are critically assessed.

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“…[10][11][12] Regarding the characteristics of the phase transition, ultra-fast 13 and spatial avalanche transitions in domains 10,14,15 have been reported. Thus, electronic control of the transition in the two terminal devices has much attracted attention; 9,[16][17][18][19] however, the control enables only a one-way transition, from insulator to metal (I-to-M). Inherently, the transition using an electric bias is caused by Joule heating, 19,20 which is unlikely to present reversible controllability of the transition.…”

Section: Introductionmentioning

confidence: 99%

Local Peltier-effect-induced reversible metal–insulator transition in VO2 nanowires

2016

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We report anomalous resistance leaps and drops in VO2 nanowires with operating current density and direction, showing reversible and nonvolatile switching. This event is associated with the metal–insulator phase transition (MIT) of local nanodomains with coexistence states of metallic and insulating phases induced by thermoelectric cooling and heating effects. Because the interface of metal and insulator domains has much different Peltier coefficient, it is possible that a significant Peltier effect would be a source of the local MIT. This operation can be realized by one-dimensional domain configuration in VO2 nanowires because one straight current path through the electronic domain-interface enables theoretical control of thermoelectric effects. This result will open a new method of reversible control of electronic states in correlated electron materials.

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Direct observation of giant metallic domain evolution driven by electric bias in VO2 thin films on TiO2(001) substrate

Cited by 33 publications

References 28 publications

Formation mechanism of a microscale domain and effect on transport properties in strainedVO2thin films onTiO2(001)

Formation mechanism of a microscale domain and effect on transport properties in strainedVO2thin films onTiO2(001)

Critical Assessment 8: Outstanding issues in electropulsing processing

Local Peltier-effect-induced reversible metal–insulator transition in VO2 nanowires

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