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

doi:10.1103/physrevlett.102.047004

Cited by 30 publications

(40 citation statements)

References 30 publications

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“…These domains are also coupled along the transverse direction c by the interplane Josephson coupling J 0 . This structure is consistent with the one proposed by Müller et al [63] from fluctuation spectroscopy measurements…”

Section: Time Dependent Ginzburg-landau Approachsupporting

confidence: 81%

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Inhomogeneous superconductivity in organic conductors: the role of disorder and magnetic field

Haddad¹,

Charfi‐Kaddour²,

Pouget³

2011

J. Phys.: Condens. Matter

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Several experimental studies have shown the presence of spatially inhomogeneous phase coexistence of superconducting and non superconducting domains in low dimensional organic superconductors. The superconducting properties of these systems are found to be strongly dependent on the amount of disorder introduced in the sample regardless of its origin. The suppression of the superconducting transition temperature Tc shows clear discrepancy with the result expected from the Abrikosov-Gor'kov law giving the behavior of Tc with impurities. Based on the time dependent Ginzburg-Landau theory, we derive a model to account for the striking feature of Tc in organic superconductors for different types of disorder by considering the segregated texture of the system. We show that the calculated Tc quantitatively agrees with experiments. We also focus on the role of superconducting fluctuations on the upper critical fields Hc2 of layered superconductors showing slab structure where superconducting domains are sandwiched by non-superconducting regions. We found that Hc2 may be strongly enhanced by such fluctuations.

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Section: Time Dependent Ginzburg-landau Approachsupporting

confidence: 81%

“…Such inhomogeneity may explain the anomalous behavior of the inplane conductivity in these materials [59]. It has been also found that the inhomogeneous superconductivity in κ(ET) 2 X compounds can also be generated by chemical [24-26, 31, 32, 55, 60] or hydrostatic pressure [10,11,[61][62][63] and irradiation [28,30,64].…”

Section: Some Experimental Factsmentioning

confidence: 99%

Inhomogeneous superconductivity in organic conductors: the role of disorder and magnetic field

Haddad¹,

Charfi‐Kaddour²,

Pouget³

2011

J. Phys.: Condens. Matter

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“…On the other hand, k-CuNCS is less correlated and positioned on the far metallic side in the phase diagram. At low temperatures, all three samples show a vanishing resistance indicating a superconducting ground state, whereas for k-Cl Ã the transition is broad and of percolative type due to the coexistence with the antiferromagnetic insulating phase [11]. Metallic k-CuNCS exhibits a negative temperature coefficient of the resistance down to about 120 K, where R(T) shows a broad maximum, the origin of which has been discussed in terms of the strongly correlated nature of the electrons, the formation of small polarons, a metal-metal phase transition, a valence instability of Cu, an order-disorder transition of the ethylene endgroups, and a crossover from localized small-polaron to coherent large-polaron behavior, see Ref.…”

Section: Experiments Single Crystals Ofmentioning

confidence: 94%

“…At high temperatures, the resistance shows a semiconducting behavior down to about 50 K, below which a step-like decrease of the resistance by almost two orders of magnitude indicates the occurrence of a metallic phase. Below 20 K, the resistance shows an increase again (with small hysteresis), which may be caused by electron localization near the Mott transition [30], before the transition into the superconducting state occurs at a Ã is due to inhomogeneous phase coexistence of the antiferromagnetic insulating and superconducting ground states [11].…”

Section: Experiments Single Crystals Ofmentioning

confidence: 97%

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

Müller

Brandenburg

Schweitzer

et al. 2012

Physica Status Solidi (b)

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We study the low-frequency dynamical properties of correlated charge carriers in various of the quasi-two-dimensional organic charge-transfer salts k-(BEDT-TTF) 2 X by means of fluctuation (noise) spectroscopy. Close to the critical endpoint of the Mott metal-insulator transition, a pronounced increase of the 1/fnoise level accompanied by a substantial shift of spectral weight to low frequencies indicates a sudden increase of the time scale of the charge fluctuations. For the less correlated, more metallic materials, we find a crossover/transition from hopping transport of more-or-less localized carriers at elevated temperatures to a low-temperature regime, where a metallic coupling of the layers allows for coherent interlayer transport of delocalized electrons.

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“…This can be understood considering the sample's position in the phase diagram closer to the Mott insulating phase resulting in a correlationinduced increase of the low-frequency fluctuations, since the charge carriers already tend to localize, an effect, which possibly is enhanced by weak static disorder [31]. Likewise, electronic phase separation in this region may enhance the low-frequency fluctuations [30,32]. Most striking, however, is the sharp and -compared to κ-D 8 -Br -strongly enhanced noise peak at T ∼ 33 K for the κ-D 8 /H 8 -Br sample cooled with q = 0.5 K/min.…”

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confidence: 99%

Critical Slowing Down of the Charge Carrier Dynamics at the Mott Metal-Insulator Transition

et al. 2015

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We report on the dramatic slowing down of the charge carrier dynamics in a quasi-two-dimensional organic conductor, which can be reversibly tuned through the Mott metal-insulator transition (MIT). At the finite-temperature critical endpoint we observe a divergent increase of the resistance fluctuations accompanied by a drastic shift of spectral weight to low frequencies, demonstrating the critical slowing down of the order parameter (doublon density) fluctuations. The slow dynamics is accompanied by non-Gaussian fluctuations, indicative of correlated charge carrier dynamics. A possible explanation is a glassy freezing of the electronic system as a precursor of the Mott MIT.The Mott metal-insulator transition (MIT), where a charge gap opens due to electron-electron interactions is a key phenomenon in modern condensed-matter physics [1], for which the understanding of various fundamental aspects remains challenging, both theoretically and experimentally [2]. Among them are the nature of the anomalous metallic state and (nano-scale) phase separation in the vicinity of the Mott transition, the understanding of the combined effects of electron-electron interactions and disorder, and the question of universality and critical behavior. In recent years, organic charge-transfer salts have proven an outstanding class of materials with model character for studying these aspects of the Mott MIT [2-5]. These materials κ-(BEDT-TTF) 2 X, composed of the organic donor molecule BEDT-TTF (bis-ethylenedithio-tetrathiafulvalene representing C 6 S 8 [C 2 H 4 ] 2 , abbreviated as ET) and a polymeric anion X, are layered systems with a quasi-twodimensional electronic structure and belong to the very few examples, where the Mott MIT is purely driven by controlling the bandwidth without symmetry breaking [6]. The bandwidth W can be covontrolled either continuously by applying hydrostatic pressure or in discrete steps at ambient pressure by varying the anion X, which mimics changes in the ratio W/U , where U is the effective on-site Coulomb repulsion [7]. Likewise, replacing the eight H-atoms of the ET molecules' C 2 H 4 ethylene endgroups (EEG) in metallic κ-(ET) 2 Cu[N(CN) 2 ]Br (κ-H 8 -Br) by D-atoms (κ-D 8 -Br) results in a chemicallyinduced shift from the metallic towards the Mott insulating state [8]. In the T -p or T -X phase diagram the MIT is represented by an S-shaped, first-order transition line which terminates in a second-order critical point (p cr. /T cr. ), see Fig. 1. Recently, the critical behavior of the charge, spin and lattice degrees of freedom at (p cr. /T cr. ) has been subject of intense research efforts [6,[9][10][11][12][13][14][15]. Despite numerous experimental and theoretical approaches, however, no consensus has been reached on the nature of the Mott criticality in κ-(ET) 2 X and the underlying universality class. Furthermore, an investigation of the critical fluctuations and the dynamic properties of the charge carriers at the critical point, in particular at low frequencies, is still lacking. From general ...

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Magnetic-Field Induced Crossover of Superconducting Percolation Regimes in the Layered Organic Mott Systemκ−(BEDT−TTF)2Cu[

Cited by 30 publications

References 30 publications

Inhomogeneous superconductivity in organic conductors: the role of disorder and magnetic field

Inhomogeneous superconductivity in organic conductors: the role of disorder and magnetic field

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

Critical Slowing Down of the Charge Carrier Dynamics at the Mott Metal-Insulator Transition

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Magnetic-Field Induced Crossover of Superconducting Percolation Regimes in the Layered Organic Mott Systemκ−(BEDT−TTF)2Cu[

Cited by 30 publications

References 30 publications

Inhomogeneous superconductivity in organic conductors: the role of disorder and magnetic field

Inhomogeneous superconductivity in organic conductors: the role of disorder and magnetic field

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

Critical Slowing Down of the Charge Carrier Dynamics at the Mott Metal-Insulator Transition

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Product

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