Different electronic transport regimes in the quasi‐two‐dimensional organic conductors κ‐(BEDT‐TTF)<sub>2</sub>X

Müller, Jens; Brandenburg, Jens; Schweitzer, Dieter; Schlueter, John A.

doi:10.1002/pssb.201100633

Cited by 5 publications

(4 citation statements)

References 38 publications

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“…This sudden slowing down of the electron dynamics is considered as a universal feature of metal-insulator transitions. The findings support the idea of electronic phase separation in the critical region of the phase diagram [356,357].…”

Section: Coexistence Regimesupporting

confidence: 85%

“…The phase separation occurs after intersection with the first-order transition line. Müller et al [356,357] established fluctuation spectroscopy as a powerful method for investigating the dynamics of correlated charge carriers in the vicinity of the Mott transition in the quasi-two-dimensional charge-transfer salts, looking in particular at κ-(d8-BEDT-TTF) 2 Cu[N(CN) 2 ]Br. The observed 1/f -type fluctuations are quantitatively very well described by a phenomenological model based on the concept of non-exponential kinetics.…”

Section: Coexistence Regimementioning

confidence: 99%

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Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Dressel

Tomić

2020

Advances in Physics

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This review provides a perspective on recent developments and their implications for our understanding of novel quantum phenomena in the physics of two-dimensional organic solids. We concentrate on the phase transitions and collective response in the charge sector, the importance of coupling of electronic and lattice degrees of freedom and stress an intriguing role of disorder. After a brief introduction to low-dimensional organic solids and their crystallographic structures, we focus on the dimensionality and interactions and emergent quantum phenomena. Important topics of current research in organic matter with sizeable electronic correlations are Mott metal-insulator phase transitions, charge order and ferroelectricity. Highly frustrated two-dimensional systems are established model compounds for studying the quantum spin liquid state and the competition with magnetic long-range order. There are also unique examples of quantum disordered state of magnetic and electric dipoles. Representative experimental results are complemented by current theoretical approaches.

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Section: Coexistence Regimesupporting

confidence: 85%

Section: Coexistence Regimementioning

confidence: 99%

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Dressel

Tomić

2020

Advances in Physics

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“…Close to the Mott critical point, we observe a dramatic and sudden slowing down of the charge carrier dynamics [27]. In contrast, for the less-correlated, more metallic systems the 1/f-noise level apparently exponentially vanishes when cooling below T Ã [28], which would be consistent with a crossover/transition from 3D coherent transport behavior at low temperatures to interlayer electronic hopping processes above T Ã . In this work, we aim to shed further light on the behavior of the electronic transport in the unusual metallic region T > T Ã at various positions X of the phase diagram.…”

mentioning

confidence: 52%

Nonlinear electronic transport in the anomalous metallic state of quasi‐2D organic superconductors κ‐(BEDT‐TTF)₂X

Rommel

Hartmann

Brandenburg

et al. 2013

Physica Status Solidi (b)

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We present measurements of the first-and third-harmonic voltage response in ac electronic transport measurements, representing the linear (ohmic) and nonlinear resistivity, respectively, of the quasi-two-dimensional (2D) organic superconductors k-(BEDT-TTF) 2 X. Nonlinear transport is a sensitive tool to probe the microgeometry of the electronic system in high-quality single crystals. For the title compounds, the normalconducting metallic state in the vicinity of the Mott metal-insulator (MI) transition and critical endpoint is known to be highly unusual. Our results reveal large current-induced intrinsic inhomogeneities, at high current densities most pronounced at the so-called T Ã anomaly, which characterizes the anomalous metallic state. The observed nonlinearities in the interlayer transport do not depend on frequency and cannot be ascribed to a simple Joule heating mechanism in a resistor network. Furthermore, we find evidence supporting the notion of electronic phase separation induced by the Mott critical endpoint. The observed dependence of the generated thirdharmonic voltage on the current density reveals a systematic behavior suggesting that current-induced electronic inhomogeneities are more pronounced for more strongly correlated systems.ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction In the last years, the quasi-twodimensional organic charge-transfer salts (BEDT-TTF) 2 X, where BEDT-TTF (bis-ethylenedithio-tetrathiafulvalene, commonly abbreviated as ET) represents C 6 S 8 [(CH 2 ) 2 ] 2 , have attracted considerable attention as model systems for studying the physics of correlated electrons and the Mott metal-insulator (MI) transition in reduced dimensions [1,2]. Recently, new routes of research also include the notion of quantum criticality and non-Fermi liquid behavior in these materials [3] as well as the simultaneous occurrence of ferroelectricity and magnetic ordering within the Mott insulating state [4]. In this paper, we address the unresolved question of the nature of the anomalous metallic state in the vicinity of the Mott transition, which -in general -can be radically different compared to the electronic band states in conventional metals. For example, close to a Mott MI transition, pseudogap behavior or an intrinsic electronic phase separation on the nanoscale is discusssed, e.g., in high-T c cuprates and organic superconductors k-(ET) 2 X with polymeric anions X À ¼ Cu[N(CN) 2 ]Z À (Z ¼ Br, Cl) or

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“…where the function g(T ) takes into account an explicit temperature dependence of the energy distribution [29][30][31] which can describe a coupling of the fluctuating entities to the measured resistance and -assuming a power law g(T ) = aT b -simply causes a vertical offset of the frequency exponent, see e.g. [27,32]. The frequency ex- ponent in the DDH model [28,31] is then given by…”

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confidence: 99%

Involvement of structural dynamics in the charge-glass formation in molecular metals

Thomas,

Saito,

Agarmani

et al. 2021

Preprint

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We present a combined study of thermal expansion and resistance fluctuation spectroscopy measurements exploring the static and dynamic aspects of the charge-glass formation in the quasi-twodimensional organic conductors θ-(BEDT-TTF)2M M (SCN)4 with M = Cs and M = Co,Zn. In these materials, the emergence of a novel charge-glass state so far has been interpreted in purely electronic terms by considering the strong frustration of the Coulomb interactions on a triangular lattice. Contrary to this view, we provide comprehensive evidence for the involvement of a structural glass-like transition at Tg ∼ 90 − 100 K. This glassy transition can be assigned to the freezing of structural conformations of the ethylene endgroups in the donor molecule with an activation energy of Ea ≈ 0.32 eV, and the concomitant slowing down of the charge carrier dynamics is well described by a model of non-exponential kinetics. These findings discolse an important aspect of the phase diagram and renders the current understanding of the charge-glass state in the whole family of θ-(BEDT-TTF)2M M (SCN)4 incomplete. Our results suggest that the entanglement of slow structural and charge-cluster dynamics due to the intimate coupling of lattice and electronic degrees of freedom determine the charge-glass formation under geometric frustration.

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Different electronic transport regimes in the quasi‐two‐dimensional organic conductors κ‐(BEDT‐TTF)₂X

Cited by 5 publications

References 38 publications

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Nonlinear electronic transport in the anomalous metallic state of quasi‐2D organic superconductors κ‐(BEDT‐TTF)₂X

Involvement of structural dynamics in the charge-glass formation in molecular metals

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Different electronic transport regimes in the quasi‐two‐dimensional organic conductors κ‐(BEDT‐TTF)2X

Cited by 5 publications

References 38 publications

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Molecular quantum materials: electronic phases and charge dynamics in two-dimensional organic solids

Nonlinear electronic transport in the anomalous metallic state of quasi‐2D organic superconductors κ‐(BEDT‐TTF)2X

Involvement of structural dynamics in the charge-glass formation in molecular metals

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Product

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Different electronic transport regimes in the quasi‐two‐dimensional organic conductors κ‐(BEDT‐TTF)₂X

Nonlinear electronic transport in the anomalous metallic state of quasi‐2D organic superconductors κ‐(BEDT‐TTF)₂X