Phase Glass is a Bose Metal: A New Conducting State in Two Dimensions

Dalidovich, Denis; Phillips, Philip

doi:10.1103/physrevlett.89.027001

Cited by 68 publications

(125 citation statements)

References 23 publications

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“…It has been found that the zero-temperature phase transition is continuous and the system behaves like a normal metal up to the phase transition point (the resistence has a finite nonzero value at T = 0). A recent theoretical study [212] of the superconductor-insulator transition in a two-dimensional array of Josephson junctions with random couplings demonstrates that the previously predicted Bose-glass phase [24,213] is a metal state that has a well defined zero-temperature limit for the conductivity.…”

Section: Superfluid-insulator and Metal-insulator Phase Transitionsmentioning

confidence: 99%

Some basic aspects of quantum phase transitions

Shopova

Uzunov

2003

Physics Reports

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Several basic problems of the theory of quantum phase transitions are reviewed. The effect of the quantum correlations on the phase transition properties is considered with the help of basic models of statistical physics. The effect of quenched disorder on the quantum phase transitions is also discussed. The review is performed within the framework of the thermodynamic scaling theory and by the most general methods of statistical physics for the treatment of phase transitions: general lengthscale arguments, exact solutions, mean field approximation, Hubbard-Stratonovich transformation, Feynman path integral approach, and renormalization group in the field theoretical variant. Some new ideas and results are presented. Outstanding theoretical problems are mentioned.

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Section: Superfluid-insulator and Metal-insulator Phase Transitionsmentioning

confidence: 99%

Some basic aspects of quantum phase transitions

Shopova

Uzunov

2003

Physics Reports

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“…Despite many theoretical treatments [8,10,11,12,13,14,15,16,17], a consensus on the mechanism behind the metallic behavior is yet to be reached. Proposed origins of the metallic behavior include bosonic interactions in the nonsuperconducting phase [10,11], contribution of fermionic quasiparticles to the conduction [12,13], and quantum phase fluctuations [14,15].In a recent paper [9] on the magnetically induced metallic behavior in Ta films, we have reported the nonlinear voltage-current (I-V ) characteristics that can be used to identify each phase. The superconducting phase is unique in having both a hysteretic I-V and an "immeasurably" small voltage response to currents below an apparent critical current I c .…”

mentioning

confidence: 99%

“…The metallic resistance can be orders of magnitude smaller than the normal state resistance (ρ n ) implying that the metallic state exists as a separate phase rather than a point in the phase diagram. Despite many theoretical treatments [8,10,11,12,13,14,15,16,17], a consensus on the mechanism behind the metallic behavior is yet to be reached. Proposed origins of the metallic behavior include bosonic interactions in the nonsuperconducting phase [10,11], contribution of fermionic quasiparticles to the conduction [12,13], and quantum phase fluctuations [14,15].…”

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confidence: 99%

Origin of Nonlinear Transport across the Magnetically Induced Superconductor-Metal-Insulator Transition in Two Dimensions

et al. 2006

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We have studied the effect of perpendicular magnetic fields and temperatures on the nonlinear electronic transport in amorphous Ta superconducting thin films. The films exhibit a magnetic field induced metallic behavior intervening the superconductor-insulator transition in the zero temperature limit. We show that the nonlinear transport in the superconducting and metallic phase is of non-thermal origin and accompanies an extraordinarily long voltage response time.In recent years, the suppression of superconductivity in two-dimensions (2D) by means of increasing disorder (usually controlled by film thickness) or applying magnetic fields has been a focus of attention. Conventional treatments [1,2,3,4,5] of electronic transport predict that in 2D the suppression of the superconductivity leads to a direct superconductor-insulator transition (SIT) in the limit of zero temperature (T = 0). This traditional view has been challenged by the observation of magnetic field (B) induced metallic behavior in amorphous MoGe [6,7,8] and Ta thin films [9]. The unexpected metallic behavior, intervening the B-driven SIT, is characterized by a drop in resistance (ρ) followed by a saturation to a finite value as T → 0. The metallic resistance can be orders of magnitude smaller than the normal state resistance (ρ n ) implying that the metallic state exists as a separate phase rather than a point in the phase diagram. Despite many theoretical treatments [8,10,11,12,13,14,15,16,17], a consensus on the mechanism behind the metallic behavior is yet to be reached. Proposed origins of the metallic behavior include bosonic interactions in the nonsuperconducting phase [10,11], contribution of fermionic quasiparticles to the conduction [12,13], and quantum phase fluctuations [14,15].In a recent paper [9] on the magnetically induced metallic behavior in Ta films, we have reported the nonlinear voltage-current (I-V ) characteristics that can be used to identify each phase. The superconducting phase is unique in having both a hysteretic I-V and an "immeasurably" small voltage response to currents below an apparent critical current I c . The metallic phase can be identified by a differential resistance (dV /dI) that increases with increasing I, whereas the insulating phase is identified by a dV /dI that decreases with increasing I. The contrasting nonlinear I-V in the metallic and insulating phase are shown in Fig. 1(a).The main purpose of this Letter is to report that the origin of the nonlinear transport, particularly in the superconducting and metallic phase, is not a simple reflection of T -dependence of ρ via the unavoidable Joule heating. We describe the effect of B and T on the nonlinear TABLE I: List of sample parameters: nominal film thickness, mean field Tc at B = 0, normal state resistivity at 4.2 K, critical magnetic field at which the resistance reaches 90% of the high field saturation value, and correlation length calculated from ξ = Φ0/2πBc where Φ0 is the flux quantum.

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“…On the other hand, the percolation paradigm 11,12 describes the films as consisting of superconducting ͑SC͒ and normal puddles; at the MR peak SC puddles exhibit a Coulomb blockade, and the percolating normal regions consist of narrow conduction channels. Yet a third theory tries to account for the low field SC-metal transition using a phase glass model 13 ͑see, however, Ref. 14 which argues against these results͒ but does not address the full MR curve.…”

mentioning

confidence: 99%

“…The phase glass model 13 focuses on the low field SCmetal transition. It, therefore, does not allow yet a full calculation of the drag resistance.…”

mentioning

confidence: 99%

Investigating the superconductor-insulator transition in thin films using drag resistance: Theoretical analysis of a proposed experiment

2009

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The magnetically driven superconductor-insulator transition in amorphous thin films ͑e.g., InO and Ta͒ exhibits several mysterious phenomena, such as a putative metallic phase and a huge magnetoresistance peak. Unfortunately, several conflicting categories of theories, particularly quantum-vortex condensation, and normal region percolation, explain key observations equally well. We present a experimental setup, an amorphous thin-film bilayer, where a drag resistance measurement would clarify the role quantum vortices play in the transition, and hence decisively point to the correct picture. We provide a thorough analysis of the device, which shows that the vortex paradigm gives rise to a drag with an opposite sign and orders of magnitude larger than the drag measured if competing paradigms apply. DOI: 10.1103/PhysRevB.80.180503 PACS number͑s͒: 74.78.Db, 73.43.Nq, 74.25.Fy, 74.78.Fk The superconducting state and the metallic Fermi-liquid form the very basis of our understanding of correlated electron systems. Nevertheless, the transition between these two phases in disordered films is shrouded in mystery. Experiments probing this transition in amorphous thin films such as Ta, MoGe, InO, and TiN used a perpendicular magnetic field and disorder ͑tuned through film thickness͒ to destroy superconductivity. But instead of a superconductor-metal transition, they observed in many cases a superconductor-insulator transition ͑SIT͒. 1 The "dirty boson" model 2 propounded the notion that the insulator is the mark of vortex condensation, and that the SIT occurs at a universal critical resistance, R ᮀ = h / 4e 2 . More recent experiments, however, showed the critical resistance to be nonuniversal. 3 Furthermore, in many field tuned experiments, a surprising metallic phase intervenes between the superconductor and insulator, 4-6 with a temperature-independent resistance below T ϳ 50 mK, and ͑at least in Ta films͒ a distinct nonlinear I-V characteristics. 7 Quite generically, 5,6,8 these films exhibit a peak in the magnetoresistance ͑MR͒ curve ͑particularly strong in InO and TiN͒ as in Fig. 1͑a͒.Two competing categories of theories may account for these phenomena. On one hand, within the quantum vortex pictures, 2,9,10 the insulating phase implies vortex condensation, the intervening metallic phase is described as uncondensed vortex liquid ͑e.g., vortex Fermi liquid͒, and the high field nonmonotonic MR indicates the appearance of a finite electronic density of states ͑DOS͒ at the Fermi level. On the other hand, the percolation paradigm 11,12 describes the films as consisting of superconducting ͑SC͒ and normal puddles; at the MR peak SC puddles exhibit a Coulomb blockade, and the percolating normal regions consist of narrow conduction channels. Yet a third theory tries to account for the low field SC-metal transition using a phase glass model 13 ͑see, however, Ref. 14 which argues against these results͒ but does not address the full MR curve. Qualitatively, both paradigms above are consistent with MR observations, and recent...

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Phase Glass is a Bose Metal: A New Conducting State in Two Dimensions

Cited by 68 publications

References 23 publications

Some basic aspects of quantum phase transitions

Some basic aspects of quantum phase transitions

Origin of Nonlinear Transport across the Magnetically Induced Superconductor-Metal-Insulator Transition in Two Dimensions

Investigating the superconductor-insulator transition in thin films using drag resistance: Theoretical analysis of a proposed experiment

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