Nonequilibrium mesoscopic superconductors in a fluctuational regime

We study temperature T and frequency ω dependence of the in-plane fluctuation conductivity of a disordered superconducting film above the critical temperature. Our calculation is based on the nonlinear sigma model within the Keldysh technique. The fluctuation contributions of different physical origin are found and analyzed in a wide frequency range. In the low-frequency range, ω ≪ T, we reproduce the known leading terms and find additional subleading ones in the Aslamazov-Larkin and the Maki-Thompson contributions to the ac conductivity. We also calculate the density of states ac correction. In the dc case these contributions logarithmically depend on the Ginzburg-Landau rate and are considerably smaller that the leading ones. However, in the ac case an external finite-frequency electromagnetic field strongly suppresses the known Aslamazov-Larkin and Maki-Thompson ac contributions, while the corresponding new terms and the density of states contribution are weakly suppressed and therefore become relevant at finite frequencies.

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“…It is determined by the terms of Eq. (18) which contain four fields that describe Cooperon degrees of freedom. We obtain…”

Section: Aslamazov-larkin Ac Conductivitymentioning

confidence: 99%

Pairing fluctuation ac conductivity of disordered thin films

Petković¹,

Vinokur²

2013

J. Phys.: Condens. Matter

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“…Among these is a central issue in condensed matter physics: the generalization of a thermodynamic phase transition to nonequilibrium conditions. There have been tantalizing reports that in systems where tuning parameters such as temperature, pressure, or magnetic field alter the symmetry, the nonequilibrium drive generates an effective temperature and the corresponding transition appears in the conventional thermal universality class [15,16]. The finding of Ref.…”

mentioning

confidence: 99%

“…Following the ideas of Ref. [16], we generalize the derivation of the Landau functional in Ref. [18] onto the DMT by including the driving current on the same footing as temperature.…”

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confidence: 99%

Scaling universality at the dynamic vortex Mott transition

et al. 2018

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The cleanest way to observe a dynamic Mott insulator-to-metal transition (DMT) without the interference from disorder and other effects inherent to electronic and atomic systems, is to employ the vortex Mott states formed by superconducting vortices in a regular array of pinning sites. Here, we report the critical behavior of the vortex system as it crosses the DMT line, driven by either current or temperature. We find universal scaling with respect to both, expressed by the same scaling function and characterized by a single critical exponent coinciding with the exponent for the thermodynamic Mott transition. We develop a theory for the DMT based on the parity reflection-time reversal (PT ) symmetry breaking formalism and find that the nonequilibrium-induced Mott transition has the same critical behavior as the thermal Mott transition. Our findings demonstrate the existence of physical systems in which the effect of a nonequilibrium drive is to generate an effective temperature and hence the transition belonging in the thermal universality class. DOI: 10.1103/PhysRevB.97.020504 A Mott insulator [1][2][3] arising from the concurrent action of the electron-electron correlations and electron trapping by a periodic atomic potential is an exemplary manifestation of many-body quantum physics [4][5][6][7][8]. A remarkable correspondence between the quantum mechanics in a D-dimensional system and the classical statistical mechanics of a D + 1-dimensional system [9] leads to the conjecture about its classical counterpart, a vortex Mott insulator that would form in a type II superconductor if the density of the superconducting vortices matches the density of the pinning sites [10,11]. Experimentally, the vortex Mott insulator was claimed in the studies of the vortex matching effect in Ref. [12], and was conclusively evidenced in Ref. [13] by measurements of the compressibility of the vortex system localized by periodic surface holes. The implications of the existence of the vortex Mott state are far reaching. First and foremost, the Mottness embraces not only the quantum but classical realm, thus offering a perfect laboratory to study quantum many-body physics by exploring classical vortex systems.An enabling discovery of the current-driven vortex Mott insulator-to-metal transition in a proximity array [14] provided the first tangible example of a dynamic Mott transition having settled the vortex quantum mechanical mapping on a firm experimental basis. That the revealed nonequilibrium critical behavior with respect to the nonequilibrium drive is the same as that of a conventional thermal Mott transition with respect to temperature raises a largely open class of questions. Among these is a central issue in condensed matter physics: the generalization of a thermodynamic phase transition to nonequilibrium conditions. There have been tantalizing reports that in systems where tuning parameters such as temperature, pressure, or magnetic field alter the symmetry, the nonequilibrium drive generates an effective temperature an...

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“…These generalized TDGL equations are analyzed numerically in Refs. [5,18].While the applicability of the TDGL equation in the superconducting region is a controversal issue, its lin-earized form can be safely employed to find the line I inst (T ) of the absolute instability of the normal state with respect to the appearance of an infinitesimally small order parameter ∆(r, t) [10,19,20]. If the transition to the superconducting state is second order, then I 1 (T ) coincides with I inst (T ).…”

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confidence: 99%

Onset of superconductivity in a voltage-biased normal-superconducting-normal microbridge

Serbyn

Skvortsov

2013

Phys. Rev. B

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We study the stability of the normal state in a mesoscopic NSN junction biased by a constant voltage V with respect to the formation of the superconducting order. Using the linearized timedependent Ginzburg-Landau equation, we obtain the temperature dependence of the instability line, Vinst(T ), where nucleation of superconductivity takes place. For sufficiently low biases, a stationary symmetric superconducting state emerges below the instability line. For higher biases, the normal phase is destroyed by the formation of a non-stationary bimodal state with two superconducting nuclei localized near the opposite terminals. The low-temperature and large-voltage behavior of the instability line is highly sensitive to the details of the inelastic relaxation mechanism in the wire. Therefore, experimental studies of Vinst(T ) in NSN junctions may be used as an effective tool to access parameters of the inelastic relaxation in the normal state.PACS numbers: 74.40. Gh, 74.78.Na, 72.15.Lh, 72.10.Di Nonequilibrium superconductivity has being attracting significant experimental and theoretical attention over decades [1][2][3], ranging from vortex dynamics [4] to the physics of the resistive state in current-carrying superconductors [5][6][7][8][9]. It was recognized long ago [10] that a superconducting wire typically has a hysteretic current voltage characteristic specified by several "critical" currents. In an up-sweep, a current exceeding the thermodynamic depairing current, I c (T ), does not completely destroy superconductivity but drives the wire into a nonstationary resistive state [11], with the excess phase winding relaxing through the formation of phase slips [12]. The resistive state continues until I 2 (T ) > I c (T ), when the wire eventually becomes normal. In the down-sweep of the current voltage characteristic, the wire remains normal until I 1 (T ) < I 2 (T ) when an emerging order parameter leads to the reduction of the wire resistance.The theoretical description of a nonequilibrium superconducting state is a sophisticated problem, requiring a simultaneous account of the nonlinear order parameter dynamics and quasiparticle relaxation under nonstationary conditions. The resulting set of equations is extremely complicated [1,4] and can be treated only numerically [13-15] (even then the stationarity of the superconducting state is often assumed [13,14]). A more intuitive but somewhat oversimplified approach is based on the a time-dependent Ginzburg-Landau (TDGL) equation for the order parameter field ∆(r, t). The TDGL approach which is generally inapplicable in the gapped phase [16], can be justified only in a very narrow vicinity of the critical temperature, T c , provided that the electron-phonon (e-ph) interaction is sufficiently strong to thermalize quasiparticles [17]. These generalized TDGL equations are analyzed numerically in Refs. [5,18].While the applicability of the TDGL equation in the superconducting region is a controversal issue, its lin-earized form can be safely employed to find the line I i...

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Nonequilibrium mesoscopic superconductors in a fluctuational regime

Abstract: PACS 73.23.-b -Electronic transport in mesoscopic systems PACS 74.45.+c -Proximity effects; Andreev effect; SN and SNS junctions PACS 74.81.Fa -Josephson junction arrays and wire networks

Cited by 10 publications

References 23 publications

Pairing fluctuation ac conductivity of disordered thin films

Pairing fluctuation ac conductivity of disordered thin films

Scaling universality at the dynamic vortex Mott transition

Onset of superconductivity in a voltage-biased normal-superconducting-normal microbridge

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