Measured temperature dependence of the intermodulation product of coplanar waveguides with s- and d-wave superconductors

Benz, G.; Wünsch, Stefan; Scherer, T.; Neuhaus, M.; Jutzi, W.

doi:10.1016/s0921-4534(01)00130-7

Cited by 24 publications

(22 citation statements)

References 8 publications

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“…1 , 2 , 3 Many experiments have been conducted to observe this effect in high-T c superconductors (HTSC). 4,5,6,7,8 Some of this work observed a linear-magnetic-fielddependent penetration depth at low temperature, in agreement with theory. 1,2 However, the quantitative, and some qualitative, details of the NLME signals in these experiments did not agree with the theory.…”

supporting

confidence: 86%

Doping-dependent nonlinear Meissner effect and spontaneous currents in high-Tcsuperconductors

et al. 2005

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We measure the local harmonic generation from superconducting thin films at microwave frequencies to investigate the intrinsic nonlinear Meissner effect near T c in zero magnetic field. Both second and third harmonic generation are measured to identify time-reversal symmetry breaking (TRSB) and time-reversal symmetric (TRS) nonlinearities. We perform a systematic doping-dependent study of the nonlinear response and find that the TRS characteristic nonlinearity current density scale follows the doping dependence of the de-pairing critical current density. We also extract a spontaneous TRSB characteristic current density scale that onsets at T c , grows with decreasing temperature, and systematically decreases in magnitude (at fixed T/T c ) with under-doping. The origin of this current scale could be Josephson circulating currents or the spontaneous magnetization associated with a TRSB order parameter.

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supporting

confidence: 86%

Doping-dependent nonlinear Meissner effect and spontaneous currents in high-Tcsuperconductors

et al. 2005

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“…4,5 Many experiments have been conducted to study 3 rd order harmonic generation or intermodulation signals, which may arise from this intrinsic nonlinearity. 6,7,8,9 On the other hand, extrinsic sources of nonlinearities dominate the nonlinear response of superconductors in most cases. They include grain boundaries, 10,11 enhanced edge currents, 12,13,14,15,16 and weakly coupled grains, 17,18,19,20,21,22,23,24 .…”

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confidence: 99%

Microwave nonlinearities of an isolated longYBa2Cu3O7−δbicrystal grain boundary

Lee

Anlage

2005

Phys. Rev. B

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We measure the local harmonic generation from an YBa 2 Cu 3 O 7-δ (YBCO) bi-crystal grain boundary to examine the local Josephson nonlinearities. Spatially resolved images of second and third harmonic signals generated by the grain boundary are shown. The harmonic generation and the vortex dynamics along the grain boundary are modeled with the Extended Resistively Shunted Josephson (ERSJ) array model, which shows reasonable agreement with the experimental data. The model also gives qualitative insight into the vortex dynamics induced in the junction by the probing current distribution. A characteristic nonlinearity scaling current density J NL ~ 5 10 5 . 1 × A/cm 2 for the Josephson nonlinearity is also extracted.

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“…Later, sensitive nonlinear microwave measurement techniques established the existence of the NLME in cuprates from the temperature dependence of the intermodulation power at low temperatures [14][15][16], although the anisotropy of the effect was not measured. Although other thermodynamic measurements have shown evidence of an anisotropic energy gap in various superconductors [17][18][19], there are no unambiguous measurements of the aNLME in cuprates, to our knowledge [20].…”

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confidence: 99%

Imaging the Anisotropic Nonlinear Meissner Effect in NodalYBa2Cu3O7−δThin-Film Superconductors

et al. 2013

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We have directly imaged the anisotropic nonlinear Meissner effect in an unconventional superconductor through the nonlinear electrodynamic response of both (bulk) gap nodes and (surface) Andreev bound states. A superconducting thin film is patterned into a compact self-resonant spiral structure, excited near resonance in the radio-frequency range, and scanned with a focused laser beam perturbation. At low temperatures, direction-dependent nonlinearities in the reactive and resistive properties of the resonator create photoresponse that maps out the directions of nodes, or of bound states associated with these nodes, on the Fermi surface of the superconductor. The method is demonstrated on the nodal superconductor YBa2Cu3O 7−δ and the results are consistent with theoretical predictions for the bulk and surface contributions.Introduction -The Meissner effect is the spontaneous exclusion of magnetic flux from the bulk of a superconductor and is one of the hallmarks of superconductivity. In the presence of a magnetic field, a superconductor must invest kinetic energy in a supercurrent flow to screen out the applied field. This reduces the free energy difference between the superconducting and normal states, resulting in a reduction in magnitude of the superconducting order parameter. This in turn leads to a field-and current-dependent magnetic penetration depth, diamagnetic moment, etc. and is referred to as the nonlinear Meissner effect (NLME). Microscopically the NLME arises when Cooper pairs at the leading edge of the current-carrying Fermi surface can de-pair into available quasi-particle states at the back-end and create a quasi-particle backflow current [1]. Conventional (fully gapped) superconductors show the strongest nonlinearities near T c , and have exponentially suppressed nonlinear response at low temperatures, T ≪ T c . Unconventional superconductors with nodes in the superconducting energy gap are expected to have a strong nonlinear Meissner effect at low temperatures, due to the nodal excitations out of the superconducting ground state [2]. In addition this nonlinear response should be anisotropic, reflecting the locations of nodes of the gap on the Fermi surface.

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Measured temperature dependence of the intermodulation product of coplanar waveguides with s- and d-wave superconductors

Cited by 24 publications

References 8 publications

Doping-dependent nonlinear Meissner effect and spontaneous currents in high-Tcsuperconductors

Doping-dependent nonlinear Meissner effect and spontaneous currents in high-Tcsuperconductors

Microwave nonlinearities of an isolated longYBa2Cu3O7−δbicrystal grain boundary

Imaging the Anisotropic Nonlinear Meissner Effect in NodalYBa2Cu3O7−δThin-Film Superconductors

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