Josephson-Junction Arrays in Transverse Magnetic Fields

Teitel, S.; Jayaprakash, C.

doi:10.1103/physrevlett.51.1999

Cited by 352 publications

(279 citation statements)

References 12 publications

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“…Nonlinearities associated with the phase transition to the zero resistance state, which are expected at lower temperatures and have been observed in some wire arrays do not appear in this experiment's range [27,28,29]. The normal state resistances, R N , of neighboring film regions were compared to assess film homogeneity and found to agree to < 7%.…”

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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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confidence: 99%

Magnetic-flux periodic response of nanoperforated ultrathin superconducting films

et al. 2006

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“…Whenever the S z S z -interaction is small, the Hamiltonian reduces to the fully-frustrated XY model in 2D, in which one cannot choose a spin configuration minimizing the spin-exchange energy for all XY-couplings. In the classical limit, similarly to a type-II superconductor, the minimal energy configuration is known to be the Abrikosov vortex lattice [46,47]. The realisation of the deep XY-regime with this particular driving protocol is limited, since |J 2 (4ζ Φ )| < 1 but, at finite S z S z -interaction a semi-classical study showed that vortices persist and can be thought of as half-skyrmion configurations of the Neél field [48][49][50].…”

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confidence: 99%

Schrieffer-Wolff Transformation for Periodically Driven Systems: Strongly Correlated Systems with Artificial Gauge Fields

2016

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We generalize the Schrieffer-Wolff transformation to periodically driven systems using Floquet theory. The method is applied to the periodically driven, strongly interacting Fermi-Hubbard model, for which we identify two regimes resulting in different effective low-energy Hamiltonians. In the nonresonant regime, we realize an interacting spin model coupled to a static gauge field with a nonzero flux per plaquette. In the resonant regime, where the Hubbard interaction is a multiple of the driving frequency, we derive an effective Hamiltonian featuring doublon association and dissociation processes. The ground state of this Hamiltonian undergoes a phase transition between an ordered phase and a gapless Luttinger liquid phase. One can tune the system between different phases by changing the amplitude of the periodic drive.

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“…A uniformly frustrated XY model [1] can be defined by the Hamiltonian [30] H = −J (jk) cos(ϕ k − ϕ j − A jk ) ,…”

Section: The Model and The Ground States A The Definition Of Thementioning

confidence: 99%

“…The uniformly frustrated XY model has been introduced by Teitel and Jayaprakash [1] for the description of a regular array of superconducting islands connected with each other by Josephson junctions (a Josephson junction array [2]) in the presence of a uniform magnetic field. During the last two decades the main attention has been concentrated on the investigation [3,4,5,6,7,8,9,10,11,12,13,14,15] of so-called fully frustrated models (on various lattices), which in terms of array correspond to having a half-integer number of the superconducting flux quanta per plaquette [3].…”

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Fluctuation-induced vortex pattern and its disordering in the fully frustratedXYmodel on a dice lattice

Korshunov

2005

Phys. Rev. B

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A highly degenerate family of states, in which the plaquettes with the same sign of vorticity form clusters of three [proposed in Phys. Rev. B 63, 134503 (2001)] is proven to really minimize the Hamiltonian of the fully frustrated XY model on a dice lattice. The harmonic fluctuations are demonstrated to be of no consequence for the removal of the accidental degeneracy of these states, so a particular vortex pattern can be stabilized only by the anharmonic fluctuations. The structure of this pattern is found and the temperature of its disordering due to the proliferation of domain walls is estimated. The extreme smallness of the fluctuation induced free energy of domain walls leads to the anomalous prominence of the finite-size effects, which prevents the observation of vortex-pattern ordering in numerical simulations. In such a situation the loss of phase coherence may be related to the dissociation of pairs of fractional vortices with the topological charges ±1/8. In a physical situation the magnetic interactions of currents in a Josephson junction array will be a more important source for the stabilization of a particular vortex pattern then the anharmonic fluctuations.

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Josephson-Junction Arrays in Transverse Magnetic Fields

Cited by 352 publications

References 12 publications

Magnetic-flux periodic response of nanoperforated ultrathin superconducting films

Magnetic-flux periodic response of nanoperforated ultrathin superconducting films

Schrieffer-Wolff Transformation for Periodically Driven Systems: Strongly Correlated Systems with Artificial Gauge Fields

Fluctuation-induced vortex pattern and its disordering in the fully frustratedXYmodel on a dice lattice

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