The Anderson-Mott transition

Belitz, D.; Kirkpatrick, T. R.

doi:10.1103/revmodphys.66.261

Cited by 1,022 publications

(1,169 citation statements)

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“…(234) - (236) beyond the Hartree-Fock approximation. His results have been rederived in customary diagrammatic theory [52,40,53]. The interference processes leading to weak localization are again neglected.…”

Section: Finkelstein Theorymentioning

confidence: 99%

Singular or non-Fermi liquids

2002

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Section: Finkelstein Theorymentioning

confidence: 99%

Singular or non-Fermi liquids

2002

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“…The latter characteristic has been ascribed to a growing fluctuation dominated regime [11]. The systematic reduction in T c0 is believed to result from disorder enhanced Coulomb repulsion effects that grow with increasing R N and possibly drive the SIT [30,31].…”

mentioning

confidence: 99%

Magnetic-flux periodic response of nanoperforated ultrathin superconducting films

et al. 2006

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We have patterned a hexagonal array of nano-scale holes into a series of ultrathin, superconducting Bi/Sb films with transition temperatures 2.65 K < Tco <5 K. These regular perforations give the films a phase-sensitive periodic response to an applied magnetic field. By measuring this response in their resistive transitions, R(T ), we are able to distinguish regimes in which fluctuations of the amplitude, both the amplitude and phase, and the phase of the superconducting order parameter dominate the transport. The portion of R(T ) dominated by amplitude fluctuations is larger in lower Tco films and thus, grows with proximity to the superconductor to insulator transition.The superconductors originally considered by BCS exhibited spectacularly sharp transitions from a finite resistance to zero resistance as a function of temperature [1]. Fluctuation effects were negligible. Presently, a great deal of attention focuses on low superfluid density superconductors for which fluctuations strongly influence and substantially broaden their phase transitions. These include the high temperature superconductors [2], and in particular, their underdoped versions [3,4,5], and ultrathin superconducting films near the superconductor to insulator transition (SIT) [6,7,8,9,10]. For the latter, resistive transitions, R(T ), can develop widths comparable to or greater than the apparent mean field transition temperature, T c0 [11].To discuss the effects of fluctuations on the R(T ) it is helpful to consider the two component superconductor order parameter ψ = |ψ 0 |e iφ . In bulk elemental superconductors, the sharp R(T ) reflect the near simultaneous appearance of a finite amplitude, |ψ 0 |, and long range coherence of the phase, φ. In low superfluid density superconductors, however, the amplitude first forms at high temperatures and phase coherence develops at lower temperatures [2,12,13,14]. High on a transition quasiparticles transiently form Cooper pairs, which enhances the quasiparticle or fermionic contribution to the conductivity, σ f . These pair or amplitude fluctuations give rise to the initial drop in R(T ) [15]. At very low values of R, a substantial Cooper pair density exists and the conductivity of these bosons, σ b , controls R(T ). σ b is limited by the motion of vortices which causes fluctuations in the phase of the cooper pair condensate. In between, a two fluid model may best describe the transport [7].Physical interpretations of the R(T ) in high sheet resistance films especially those near the SIT relies heavily on distinguishing the amplitude and phase fluctuation dominated regimes [3,4,5,6]. Most often, explicit models for σ f (T ) and σ b (T ) do not exist as a guide and qualitative arguments must prevail. In this paper we present the magnetic flux response of the R(T ) of very low superfluid density (high sheet resistance) [11,16] films patterned with a nanoscale array of holes. We use the quality of the flux response at different points along their transitions to determine the presence of well-defined vortic...

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“…The additional complexity of competing orders such superconductivity with charge density wave (CDW) or magnetism makes this problem one of the most challenging frontiers in physics. [2][3][4][5] A large body of literature is devoted to this interplay in nearly magnetic materials. 6 The interplay of disorder and superconductivity in CDW materials have been less explored than its magnetic analog.…”

Section: Introductionmentioning

confidence: 99%

Superconducting order from disorder in 2H-TaSe 2− x S x

Deng

Wang

et al. 2017

npj Quant Mater

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We report on the emergence of robust superconducting order in single crystal alloys of TaSe 2−x S x (0 ≤ × ≤ 2). The critical temperature of the alloy is surprisingly higher than that of the two end compounds TaSe 2 and TaS 2 . The evolution of superconducting critical temperature T c (x) correlates with the full width at half maximum of the Bragg peaks and with the linear term of the high-temperature resistivity. The conductivity of the crystals near the middle of the alloy series is higher or similar than that of either one of the end members 2H-TaSe 2 and/or 2H-TaS 2 . It is known that in these materials superconductivity is in close competition with charge density wave order. We interpret our experimental findings in a picture where disorder tilts this balance in favor of superconductivity by destroying the charge density wave order.npj Quantum Materials (2017) 2:11 ; doi:10.1038/s41535-017-0016-9 INTRODUCTIONThe interplay of disorder and interactions is a fruitful area of investigation. In the absence of electron-electron interactions, disorder can turn a metallic system into an Anderson insulator, 1 but can remain metallic when interactions are important. The additional complexity of competing orders such superconductivity with charge density wave (CDW) or magnetism makes this problem one of the most challenging frontiers in physics. 2-5 A large body of literature is devoted to this interplay in nearly magnetic materials. 6 The interplay of disorder and superconductivity in CDW materials have been less explored than its magnetic analog.Superconductivity and CDW are traditionally viewed as weakcoupling Fermi surface instabilities due to electron-phonon coupling. 7 Arguments have been made both for their cooperation and competition. 8,9 Hexagonal transition metal dichalcogenide 2H-TaSe 2 (P63/mmc space group) undergoes a second-order transition to an incommensurate CDW at 122 K followed by a first-order lock-in transition to a commensurate CDW (CCDW) phase at 90 K, eventually becoming superconducting below 0.14 K upon cooling. 10, 11 2H-TaS 2 has T c = 0.8 K below an in-plane CCDW at 78 K. 10,12 The CDW mechanism in 2H-TaSe 2 involves an electron instability in the bands nested away from the Fermi surface, whereas 2H-TaS 2 features a polar charge and orbital order. 13,14 CDW in 2H-TaSe 2 is dominated by hopping between next-nearest neighbors that creates three weakly coupled triangular sublattices. 15 It is of interest to note that the 2H-TaSe 2 is quasi-twodimensional (2D) metal with pseudogap and with c-axis resistivity 25-50 times higher than the in-plane resistivity, i.e., ρ c (T) >> ρ ab (T). 10,13,[16][17][18] Here, we report that in the 2H-TaSe 2−x S x alloy series the CDW is suppressed and the superconductivity is maximized with

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The Anderson-Mott transition

Cited by 1,022 publications

References 356 publications

Singular or non-Fermi liquids

Singular or non-Fermi liquids

Magnetic-flux periodic response of nanoperforated ultrathin superconducting films

Superconducting order from disorder in 2H-TaSe 2− x S x

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