Nonlinear microwave properties of high<i>T</i><sub>c</sub>thin films

Velichko, A. V.; Lancaster, M.J.; Porch, Adrian

doi:10.1088/0953-2048/18/3/r02

Cited by 34 publications

(36 citation statements)

References 71 publications

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“…15. This hysteretic behavior enables an experimental separation of the vortex contribution to R i from reversible mechanisms due to sound generation 78 , dielectric losses in the substrate 79,80 etc. The total surface resistance R s can be written as a sum of the vortex component R i and the BCS resistance…”

Section: B Residual Surface Resistance At B0 ≪ Bvmentioning

confidence: 99%

Dynamics of vortex penetration, jumpwise instabilities, and nonlinear surface resistance of type-II superconductors in strong rf fields

2008

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We consider nonlinear dynamics of a single vortex in a superconductor in a strong rf magnetic field B0 sin ωt. Using the London theory, we calculate the dissipated power Q(B0, ω), and the transient time scales of vortex motion for the linear Bardeen-Stephen viscous drag force, which results in unphysically high vortex velocities during vortex penetration through the oscillating surface barrier. It is shown that penetration of a single vortex through the ac surface barrier always involves penetration of an antivortex and the subsequent annihilation of the vortex antivortex pairs. Using the nonlinear Larkin-Ovchinnikov (LO) viscous drag force at higher vortex velocities v(t) results in a jump-wise vortex penetration through the surface barrier and a significant increase of the dissipated power. We calculate the effect of dissipation on nonlinear vortex viscosity η(v) and the rf vortex dynamics and show that it can also result in the LO-type behavior, instabilities, and thermal localization of penetrating vortex channels. We propose a thermal feedback model of η(v), which not only results in the LO dependence of η(v) for a steady-state motion, but also takes into account retardation of temperature field around rapidly accelerating vortex, and a long-range interaction with the surface. We also address the effect of pinning on the nonlinear rf vortex dynamics and the effect of trapped magnetic flux on the surface resistance Rs calculated as a function or rf frequency and field. It is shown that trapped flux can result in a temperature-independent residual resistance Ri at low T , and a hysteretic low-field dependence of Ri(B0), which can decrease as B0 is increased, reaching a minimum at B0 much smaller than the thermodynamic critical field Bc. We propose that cycling of rf field can reduce Ri due to rf annealing of magnetic flux which is pumped out by rf field from the thin surface layer of the order of the London penetration depth.

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Section: B Residual Surface Resistance At B0 ≪ Bvmentioning

confidence: 99%

Dynamics of vortex penetration, jumpwise instabilities, and nonlinear surface resistance of type-II superconductors in strong rf fields

2008

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“…Nonlinearities in superconducting films and resonators are widely studied in the context of high-T c superconductors for different applications, 6 with critical temperatures ranging from 9 K ͑niobium͒ to 87 K ͑YBCO͒. Nonlinear behavior is found to originate from thermal instabilities due to local hot spots 7,8 and vortices [9][10][11] leading to a power-dependent surface impedance.…”

Section: Introductionmentioning

confidence: 99%

“…14,19 In most mechanisms, the superconductor film quality plays a crucial role in the power handling. 6 Quasiparticle heating is sometimes mentioned but neglected due to the relatively high thermal conductivity of high-T c superconductors. Where thermal effects play a role, they are caused by local heating due to film inhomogeneities 8,20 or measured by an external resonant probe.…”

Section: Introductionmentioning

confidence: 99%

Readout-power heating and hysteretic switching between thermal quasiparticle states in kinetic inductance detectors

Visser

Withington

Goldie

2010

Journal of Applied Physics

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A model is presented for readout-power heating in kinetic inductance detectors. It is shown that the power dissipated by the readout signal can cause the temperature of the quasiparticle system in the superconducting resonator to switch between well-defined states. At low readout powers, only a single solution to the heat balance equation exists, and the resonance curve merely distorts as the readout power is increased. At high readout powers, three states exist, two of which are stable, and the resonance curve shows hysteretic switching. The power threshold for switching depends on the geometry and material used but is typically around Ϫ70 dBm for Aluminum resonators. A comprehensive set of simulations is reported, and a detailed account of the switching process is given. Experimental results are also shown, which are in strong qualitative agreement with the simulations. The general features of the model are independent of the precise cooling function, and are even applicable for resonators on suspended, thermally isolated, dielectric membranes, where an increase in quasiparticle lifetime is expected. We discuss various extensions to the technique, including the possibility of recovering the cooling function from large-signal measurements of the resonance curve.

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“…In spite of considerable effort, an universal model able to explain all the observed features has not yet been developed. Reviews of the results on the nonlinear MW surface impedance and the proposed models have been discussed in [5,6,8,28]. A common characteristic is that for H MW < H c1 j , R s varies quadratically with the frequency and the field-induced Z s variations are small and not easily detectable [8,28] [29,30]; others describe the nonlinearity of Z s considering dynamics of Josephson fluxons in grain boundaries [28].…”

Section: Resultsmentioning

confidence: 99%

“…Reviews of the results on the nonlinear MW surface impedance and the proposed models have been discussed in [5,6,8,28]. A common characteristic is that for H MW < H c1 j , R s varies quadratically with the frequency and the field-induced Z s variations are small and not easily detectable [8,28] [29,30]; others describe the nonlinearity of Z s considering dynamics of Josephson fluxons in grain boundaries [28]. It has been suggested that, in order to recognize the process responsible for the field-induced variations of Z s , an useful parameter is r ≡ X s / R s , though in some cases no correlation between R s and X s has been observed [8].…”

Section: Resultsmentioning

confidence: 99%

Tunable coaxial cavity resonator for linear and nonlinear microwave characterization of superconducting wires

Gallitto¹,

Bonsignore²,

Vigni³

et al. 2011

Supercond. Sci. Technol.

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We discuss experimental results obtained using a tunable cylindrical coaxial cavity resonator constituted by an outer Cu cylinder and an inner bulk Bi 1.8 Pb 0.26 Sr 2 Ca 2 Cu 3 O 10+x cylinder. We have used this device to investigate the microwave response of the superconducting wire, both in the linear and nonlinear regimes. In particular, by tuning the different modes of the cavity to make them resonant at exactly harmonic frequencies, we have detected the power emitted by the superconductor at the second-and third-harmonic frequency of the driving field. The results obtained in the nonlinear regime, whether for the microwave surface impedance or the harmonic emission, are discussed in the framework of the models reported in the literature for granular superconductors. The use of this kind of device could be of great interest to investigate and characterize wires of large dimensions, to be used for implementing superconducting-based microwave devices.

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Nonlinear microwave properties of highT_cthin films

Cited by 34 publications

References 71 publications

Dynamics of vortex penetration, jumpwise instabilities, and nonlinear surface resistance of type-II superconductors in strong rf fields

Dynamics of vortex penetration, jumpwise instabilities, and nonlinear surface resistance of type-II superconductors in strong rf fields

Readout-power heating and hysteretic switching between thermal quasiparticle states in kinetic inductance detectors

Tunable coaxial cavity resonator for linear and nonlinear microwave characterization of superconducting wires

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Nonlinear microwave properties of highTcthin films

Cited by 34 publications

References 71 publications

Dynamics of vortex penetration, jumpwise instabilities, and nonlinear surface resistance of type-II superconductors in strong rf fields

Dynamics of vortex penetration, jumpwise instabilities, and nonlinear surface resistance of type-II superconductors in strong rf fields

Readout-power heating and hysteretic switching between thermal quasiparticle states in kinetic inductance detectors

Tunable coaxial cavity resonator for linear and nonlinear microwave characterization of superconducting wires

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Nonlinear microwave properties of highT_cthin films