Phase Separation in Doped Mott Insulators

Yee, Chuck-Hou

doi:10.1103/physrevx.5.021007

Cited by 30 publications

(38 citation statements)

References 47 publications

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“…We can rule out a percolative, first-order transition as the explanation [24,25]. A possible explanation involves disorder introduced by the Sr dopants and which causes the carriers to localize; i.e., the MIT is of Mott-Anderson type [43].…”

Section: -3mentioning

confidence: 99%

Response of the Lattice across the Filling-Controlled Mott Metal-Insulator Transition of a Rare Earth Titanate

et al. 2017

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The lattice response of a prototype Mott insulator, SmTiO 3 , to hole doping is investigated with atomic-scale spatial resolution. SmTiO 3 films are doped with Sr on the Sm site with concentrations that span the insulating and metallic sides of the filling-controlled Mott metalinsulator transition (MIT). The GdFeO 3 -type distortions are investigated using an atomic resolution scanning transmission electron microscopy technique that can resolve small lattice distortions with picometer precision. We show that these distortions are gradually and uniformly reduced as the Sr concentration is increased without any phase separation. Significant distortions persist into the metallic state. The results present a new picture of the physics of this prototype filling-controlled MIT, which is discussed.

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Section: -3mentioning

confidence: 99%

Response of the Lattice across the Filling-Controlled Mott Metal-Insulator Transition of a Rare Earth Titanate

et al. 2017

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“…Mott-like transition, [18][19][20] but also strong coupling to phonon modes and doubling of the unit-cell. [21] In VO2 thin films and nano-beams, the transition develops through a spatially phase separated state [8,10,22] that may affect the dynamics of the transition.Phase separation is complicated by at least one additional insulating phase for which a solid state triple point was identified. [23] Further modification can be achieved by substrate and local strain, which alter the VO2 electronic properties [18] or control the phase separation.…”

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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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“…Phase separation at the Mott transition is theoretically well-studied [4][5][6][7][8][9] , establishing the coexistence between the undoped Mott insulator and a doped phase, either a normal metal or pseudogapped state. Extensive work has also examined Mott systems in inhomogeneous geometries, exploring correlated surfaces and heterostructures, where the Coulomb repulsion or hopping is varied spatially [10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Interfaces in coexisting metals and Mott insulators

Lee

Yee

2017

Phys. Rev. B

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Motivated by the direct observation of electronic phase separation in first-order Mott transitions, we model the interface between the thermodynamically coexisting metal and Mott insulator. We show how to model the required slab geometry and extract the electronic spectra. We construct an effective Landau free energy and compute the variation of its parameters across the phase diagram. Finally, using a linear mixture of the density and double-occupancy, we identify a natural Ising order parameter which unifies the treatment of the bandwidth and filling controlled Mott transitions.

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Phase Separation in Doped Mott Insulators

Cited by 30 publications

References 47 publications

Response of the Lattice across the Filling-Controlled Mott Metal-Insulator Transition of a Rare Earth Titanate

Response of the Lattice across the Filling-Controlled Mott Metal-Insulator Transition of a Rare Earth Titanate

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

Interfaces in coexisting metals and Mott insulators

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