Mott Physics near the Insulator-To-Metal Transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>NdNiO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>

Stewart, M. K.; Liu, Jian; Kareev, M.; Chakhalian, Jak; Basov, D. N.

doi:10.1103/physrevlett.107.176401

Cited by 92 publications

(92 citation statements)

References 33 publications

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“…In addition, the nontrivial charge and orbital orderings in TMOs are highly susceptible to local and external stimuli such as thermal excitation [4], strain [5][6][7] or light illumination [8][9][10]. The resultant phase transitions are often accompanied by inevitable mesoscopic electronic and/or magnetic inhomogeneities [11][12][13][14], making it extremely difficult to distinguish emergent single phase properties from area-averaging phenomena originating from a mixed state [13,[15][16][17]. As a result, experimental observations strongly depend on the particularities of the samples and measurement techniques, posing difficulties in interpreting the results obtained with complementary experimental approaches.…”

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confidence: 99%

Phase transition in bulk single crystals and thin films ofVO2by nanoscale infrared spectroscopy and imaging

et al. 2015

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We have systematically studied a variety of vanadium dioxide (VO 2 ) crystalline forms, including bulk single crystals and oriented thin films, using infrared (IR) near-field spectroscopic imaging techniques. By measuring the IR spectroscopic responses of electrons and phonons in VO 2 with sub-grain-size spatial resolution (~20 nm), we show that epitaxial strain in VO 2 thin films not only triggers spontaneous local phase separations but also leads to intermediate electronic and lattice states that are intrinsically different from those found in bulk. Generalized rules of strain and symmetry dependent mesoscopic phase inhomogeneity are also discussed. These results set the stage for a comprehensive understanding of complex energy landscapes that may not be readily determined by macroscopic approaches.

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Section: Introductionmentioning

confidence: 99%

Phase transition in bulk single crystals and thin films ofVO2by nanoscale infrared spectroscopy and imaging

et al. 2015

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“…Phase separation has been recently reported in ultrathin films. [25] Conflicting evidence for the presence of charge ordering [26][27][28][29] and the role of electronic vs. magnetic correlations [28,30] point to the intricate nature of this transition (see for example [31] and references therein).In typical T-driven MIT measurements, the temperature is ramped up from low to high temperatures, driving the system from an insulating to a metallic phase. To observe the memory effect, we perform a series of resistance vs. temperature (R-T) measurements, where we interrupt the usual temperature rise with a reversal of the ramp from heating to cooling at a specific temperature, TH, which lies within the transition region.…”

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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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“…The insulating state is characterized by a two-sublattice symmetry breaking, with the Ni on one sublattice having a decreased Ni-O bond length and the Ni on the other having an increased mean Ni-O bond length. While the materials are sometimes classified as Mott/charge-transfer materials [2][3][4], the Mott picture does not account for the association of insulating behavior with bond disproportionation. Charge ordering has been extensively discussed [1,[5][6][7][8] but charge ordering in the naive sense of a change in the Ni valence between the two sublattices is expected to be suppressed by the large repulsive d-d interaction U on the Ni site and appears to be ruled out by very recent soft X-ray resonant diffraction data [9].…”

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Site-Selective Mott Transition in Rare-Earth-Element Nickelates

2012

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A combination of density functional and dynamical mean field theory calculations are used to show that the remarkable metal-insulator transition in the rare earth nickelate perovskites arise from a site-selective Mott phase, in which the d-electrons on a half of the Ni ions are localized to form a fluctuating moment while the d-electrons on other Ni ions form a singlet with holes on the surrounding oxygen ions. The calculation reproduces key features observed in the nickelate materials, including an insulating gap in the paramagnetic state, a strong variation of static magnetic moments among Ni sites and an absence of "charge order". A connection between structure and insulating behavior is documented. The site-selective Mott transition may be a more broadly applicable concept in the description of correlated materials.

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Mott Physics near the Insulator-To-Metal Transition inNdNiO3

Cited by 92 publications

References 33 publications

Phase transition in bulk single crystals and thin films ofVO2by nanoscale infrared spectroscopy and imaging

Phase transition in bulk single crystals and thin films ofVO2by nanoscale infrared spectroscopy and imaging

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

Site-Selective Mott Transition in Rare-Earth-Element Nickelates

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