First-order reversal curve measurements of the metal-insulator transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>VO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>: Signatures of persistent metallic domains

Ramírez, Juan Gabriel; Sharoni, Amos; Dubi, Yonatan; Gómez, M. E.; Schuller, Iván K.

doi:10.1103/physrevb.79.235110

Cited by 99 publications

(86 citation statements)

References 35 publications

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“…It is known that even high quality VO 2 thin films exhibit inhomogeneities, such as nonstoichiometry and grain boundaries, which are responsible for the microscopic phase coexistence far below the bulk MIT temperature [13,26,27]. Photogenerated electron-hole pairs can be separated due to band bending at these metalinsulator phase boundaries.…”

Section: Discussionmentioning

confidence: 99%

“…This is the expected 4 × 10 −3Å−1 shift between the monoclinic phase at 300 K and the tetragonal phase at 354 K [25]. Near the MIT, a coexistence of the high-and low-temperature phases is known to occur [13,26,27]. After approximately 45 minutes of x-ray exposure at the location indicated by the black ellipse in Fig.…”

Section: Fig 2 (Color Online) (A)mentioning

confidence: 99%

“…The MIT in VO 2 occurs above room temperature (340 K) with a simultaneous structural phase transition (SPT), changing from a semiconductor with a monoclinic lattice to a metal with a tetragonal lattice [5,11,12]. There is a variation of MIT temperatures between VO 2 grains, even for high quality samples [13]. Thus, metallic inclusions exist well below the bulk MIT temperature.…”

Section: Introductionmentioning

confidence: 99%

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X-ray-induced persistent photoconductivity in vanadium dioxide

et al. 2014

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The resistivity of vanadium dioxide (VO2) decreased by over one-order of magnitude upon localized illumination with x-rays at room temperature. Despite this reduction, the structure remained in the monoclinic phase and had no signature of the high-temperature tetragonal phase that is usually associated with the lower resistance. Once illumination ceased, relaxation to the insulating state took tens of hours near room temperature. However, a full recovery of the insulating state was achieved within minutes by thermal cycling. We show that this behavior is consistent with random local-potential fluctuations and random distribution of discrete recombination sites used to model residual photoconductivity.

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Section: Discussionmentioning

confidence: 99%

Section: Fig 2 (Color Online) (A)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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X-ray-induced persistent photoconductivity in vanadium dioxide

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“…As mentioned above, the use of the R X L X branch has been suggested before to account for the coexistence of conventional insulating areas and conducting domains in the films. 7,9 The parallel arrangement of the conventional RC and additional R X L X branch may suggest a predominantly parallel arrangement of such two phases.…”

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“…6 The phase-coexistence in VO 2 across the MIT is particularly intriguing, because the metallic phase starts to form locally far below the macroscopic MIT in the form of persistent metallic domains within the insulating matrix. 7 It was argued from current-voltage measurements that a thermal filament or thread forms at large enough bias voltage (see for example Ref. 8 and references therein).…”

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Ultra-thin filaments revealed by the dielectric response across the metal-insulator transition in VO2

Ramírez

Schmidt

Sharoni

et al. 2013

Applied Physics Letters

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Ramp‐Reversal Memory and Phase‐Boundary Scarring in Transition Metal Oxides

et al. 2017

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Transition metal oxides (TMOs) are complex electronic systems which exhibit a multitude of collective phenomena. Two archetypal examples are VO2 and NdNiO3, which undergo a metal-insulator phase-transition (MIT), the origin of which is still under debate. Here we report the discovery of a memory effect in both systems, manifest through an increase of resistance at a specific temperature, which is set by reversing the temperature-ramp from heating to cooling during the MIT. The characteristics of this ramp-reversal memory effect do not coincide with any previously reported history or memory effects in manganites, electronglass or magnetic systems. From a broad range of experimental features, supported by theoretical modelling, we find that the main ingredients for the effect to arise are the spatial Submitted to 22222222224222 phase-separation of metallic and insulating regions during the MIT and the coupling of lattice strain to the local critical temperature of the phase transition. We conclude that the emergent memory effect originates from phase boundaries at the reversal-temperature leaving "scars" in the underlying lattice structure, giving rise to a local increase in the transition temperature.The universality and robustness of the effect shed new light on the MIT in complex oxides.TMOs are a hallmark example of complex electron systems; the competition between charge, spin, strain, lattice, oxidation and other degrees of freedom, having similar energy scales, give rise to numerous collective phenomena [1][2][3] including superconductivity, [4] colossal magnetoresistance [5] and metal-insulator transitions (MIT). [6] In many thin film TMOs which exhibit a temperature (T)-driven phase transition, complexity is manifest through the coexistence of multiple phases where a single phase is expected, [7][8][9][10][11] providing the setting required for emergent phenomena to develop.[1]An intriguing feature found in many of the systems that exhibit the aforementioned phenomena, is the appearance of internal memory, where the system's properties (e.g. resistance or magnetization) depend on the measurement history. Such memory effects appear in various forms and measurement settings, having very different microscopic origins, many of which are still poorly understood. Examples include dynamical memory and slow relaxation in electron-glass systems such as amorphous oxides, [12,13] spatially phase-separated memory in colossal-magnetoresistance manganites, [14] shape-memory in martensitic alloys, [15] and more. [16,17] Here we report the appearance of an unexpected memory effect within the MIT in two prototypical examples of complex TMOs, namely VO2 and NdNiO3 (NNO). The characteristics of the observed effect differ substantially from those of previously reported memory effects, indicating a different microscopic origin.VO2 and NNO both exhibit an MIT, however its features and microscopic origin are quite different. In VO2 the MIT occurs above room temperature, ~340 K, and is accompanied by a structural transition from...

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First-order reversal curve measurements of the metal-insulator transition inVO2: Signatures of persistent metallic domains

Cited by 99 publications

References 35 publications

X-ray-induced persistent photoconductivity in vanadium dioxide

X-ray-induced persistent photoconductivity in vanadium dioxide

Ultra-thin filaments revealed by the dielectric response across the metal-insulator transition in VO2

Ramp‐Reversal Memory and Phase‐Boundary Scarring in Transition Metal Oxides

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