Superconducting phase transitions in a<i>kagomé</i>wire network

Higgins, M. J.; Xiao, Ying; Bhattacharya, S.; Chaikin, P. M.; Sethuraman, S.; Bojko, Richard; Spencer, David

doi:10.1103/physrevb.61.r894

Cited by 31 publications

(37 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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%.…”

mentioning

confidence: 99%

Magnetic-flux periodic response of nanoperforated ultrathin superconducting films

et al. 2006

View full text Add to dashboard Cite

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...

show abstract

mentioning

confidence: 99%

Magnetic-flux periodic response of nanoperforated ultrathin superconducting films

et al. 2006

View full text Add to dashboard Cite

show abstract

“…The authors of Ref. [16] have interpreted this as an evidence for the presence of two phase transitions.…”

Section: Discussionmentioning

confidence: 96%

“…Recent experimental investigation of the aluminum wire network with kagomé structure [16] has demonstrated for φ = φ 0 /2 the presence on the current-volatage curve of the regions corresponding to different mechanisms of dissipation, one of which (with an algebraic behavior) can be associated with unbinding of vortex pairs and the other with spreading of domains with inversed chiralities [44]. The authors of Ref.…”

Section: Discussionmentioning

confidence: 99%

“…The other class of physical systems, which allows for experimental realization of the considered model, consists of Josephson junction arrays [15] and two-dimensional superconducting wire networks [16] in perpendicular magnetic field. In such systems the role of ϕ i is played by the phase of the superconducting order parameter, and equivalence with the antiferromagnetic XY model is achieved when the magnitude of the magnetic field corresponds to half-integer number of superconducting flux quanta per each triangular plaquette.…”

Section: (B)mentioning

confidence: 99%

See 1 more Smart Citation

Phase transitions in the antiferromagneticXYmodel with akagomélattice

Korshunov

2002

Phys. Rev. B

View full text Add to dashboard Cite

The ground state of the antiferromagnetic XY model with a kagomé lattice is known to be characterized by a well developed accidental degeneracy. As a consequence the phase transition in this system consists in unbinding of pairs of fractional vortices. Addition of the next-to-nearest neighbor (NNN) interaction leads to stabilization of the long-range order in chirality (or staggered chirality). We show that the phase transition, related with destruction of this long-range order, can happen as a separate phase transition below the temperature of the fractional vortex pairs unbinding only if the NNN coupling is extremely weak, and find how the temperature of this transition depends on coupling constants. We also demonstrate that the antiferromagnetic ordering of chiralities and, accordingly, the presence of the second phase transition are induced by the free energy of spin wave fluctuations even in absence of the NNN coupling.

show abstract

“…More recently, special attention is given to highly frustrated systems which are unable to simultaneously satisfy the competing interactions and consequently have the highly degenerate ground states. 2,3,4,5,6,7,8,9,10,11,12 Understanding how a highly frustrated system orders or fails to order is one of most challenging problems in current condensed matter physics.The infinite degeneracy of the ground state has been suggested in the systems on the triangular, kagome, honeycomb, or dice lattice with the formation of zero-energy domain walls in the ordered vortex state. 3,4,7,8,11,12 The common cause to lift the accidental degeneracy is thermal fluctuations in the continuous phase variable, that is, spin waves.…”

mentioning

confidence: 99%

Superconducting transitions in frustrated Josephson-junction arrays on a dice lattice

Baek

Yun

Choi

2008

Physica C: Superconductivity

View full text Add to dashboard Cite

Transport measurements are carried out on dice Josephson-junction arrays with the frustration index f = 1/3 and 1/2 which possess, within the limit of the XY model, an accidental degeneracy of the ground states as a consequence of the formation of zero-energy domain walls. The measurements demonstrate that both the systems undergo a phase transition to a superconducting vortex-ordered state at considerably high temperatures. The experimental findings are in apparent contradiction with the theoretical expectation that frustration effects in the f = 1/3 system are particularly strong enough to suppress a vortex-ordering transition down to near zero temperature. The data for f = 1/2 are more consistent with theoretical evaluations. The agreement between the experiments and the Monte Carlo simulations of a XY model for f = 1/3 suggests that the order-from-disorder mechanism for the removal of an accidental degeneracy may still be effective in the f = 1/3 system. The transport data also reveal that the dice arrays with zero-energy domain walls experience a much slower critical relaxation than other frustrated arrays only with finite-energy walls.PACS numbers: 74.81. Fa, 75.10.Hk, 64.60.Cn Vortex matters in Josephson-junction arrays (JJA's) and superconducting wire networks exposed to a magnetic field have been extensively studied in recent years. 1Studies of the systems of a variety of geometries have been concentrated especially on the nature of ordering transitions and excitations in the ordered state. More recently, special attention is given to highly frustrated systems which are unable to simultaneously satisfy the competing interactions and consequently have the highly degenerate ground states. 2,3,4,5,6,7,8,9,10,11,12 Understanding how a highly frustrated system orders or fails to order is one of most challenging problems in current condensed matter physics.The infinite degeneracy of the ground state has been suggested in the systems on the triangular, kagome, honeycomb, or dice lattice with the formation of zero-energy domain walls in the ordered vortex state. 3,4,7,8,11,12 The common cause to lift the accidental degeneracy is thermal fluctuations in the continuous phase variable, that is, spin waves. 3,8,11,12 The difference in free energy of the fluctuations forces many systems to select a particular vortex pattern at finite temperatures. This mechanism of lifting an accidental degeneracy is often referred to as order-from-disorder. Frustrated JJA's on the dice (or T 3 ) lattice have attracted recent attention because of the possibility that the order-from-disorder mechanism for the removal of an accidental degeneracy may not be effective in the systems. Theoretical evaluations 12 on the frustrated XY model, which most closely represents a JJA in a magnetic field, have demonstrated that for the frustration index (defined as the magnetic flux through a rhombus tile in units of flux quantum) f = 1/3, frustration effects on a dice array are particularly large and the system fails to order down to zero tempe...

show abstract

Superconducting phase transitions in akagoméwire network

Cited by 31 publications

References 14 publications

Magnetic-flux periodic response of nanoperforated ultrathin superconducting films

Magnetic-flux periodic response of nanoperforated ultrathin superconducting films

Phase transitions in the antiferromagneticXYmodel with akagomélattice

Superconducting transitions in frustrated Josephson-junction arrays on a dice lattice

Contact Info

Product

Resources

About