Microwave power-induced flux penetration and loss in high-temperature superconductors

Portis, A. M.

doi:10.1007/bf00618131

Cited by 29 publications

(10 citation statements)

References 46 publications

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“…Numerous research groups investigate pinning and flux flow by microwave absorption, see e.g. Blazey et al (1988), Portis et al (1988), Shridar et al (1989), Giura et al (1992), Kessler et al (1994), Gough and Exon (1994), Blackstead et al (1994), Lofland (1995), Golosovsky ( , 1992Golosovsky ( , 1993Golosovsky ( , 1994Golosovsky ( , 1995, and the reviews by Piel and Müller (1991), Portis (1992), andDumas et al (1995). Unexpected sharp magnetoabsorption resonances with cyclotronic and anticyclotronic polarisation were observed in BSCCO at 30 and 47 MHz in fields up to 7 T by Tsui et al (1994) and are explained by .…”

Section: Vortex Glass Scalingmentioning

confidence: 99%

The flux-line lattice in superconductors

1995

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Magnetic flux can penetrate a type-II superconductor in form of Abrikosov vortices (also called flux lines, flux tubes, or fluxons) each carrying a quantum of magnetic flux φ 0 = h/2e. These tiny vortices of supercurrent tend to arrange in a triangular flux-line lattice (FLL) which is more or less perturbed by material inhomogeneities that pin the flux lines, and in high-T c superconductors (HTSC's) also by thermal fluctuations. Many properties of the FLL are well described by the phenomenological Ginzburg-Landau theory or by the electromagnetic London theory, which treats the vortex core as a singularity. In Nb alloys and HTSC's the FLL is very soft mainly because of the large magnetic penetration depth λ: The shear modulus of the FLL is c 66 ∼ 1/λ 2 , and the tilt modulus c 44 (k) ∼ (1 + k 2 λ 2 ) −1 is dispersive and becomes very small for short distortion wavelength 2π/k ≪ λ. This softness is enhanced further by the pronounced anisotropy and layered structure of HTSC's, which strongly increases the penetration depth for currents along the c-axis of these (nearly uniaxial) crystals and may even cause a decoupling of two-dimensional vortex lattices in the Cu-O layers. Thermal fluctuations and softening may "melt" the FLL and cause thermally activated depinning of the flux lines or of the two-dimensional "pancake vortices" in the layers. Various phase transitions are predicted for the FLL in layered HTSC's. Although large pinning forces and high critical currents have been achieved, the small depinning energy so far prevents the application of HTSC's as conductors at high temperatures except in cases when the applied current and the surrounding magnetic field are small.

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Section: Vortex Glass Scalingmentioning

confidence: 99%

The flux-line lattice in superconductors

1995

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“…The geometry factors for the two parts are G0 = c.i0a1n(.) (3) and G = coii0b1n(.) (4) where a and b are the center conductor and outer wall radii respectively.…”

Section: Measurement Techniquementioning

confidence: 99%

Generation of intermodulation products by granular YBa 2 Cu 3 O 7-x thick films

et al. 1995

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Two tone tests performed on resonators and filters fabricated from YBCO thick film coated, three dimensional resonators, indicate the importance of understanding intermodulation distortion. The films in this investigation were produced by reactive texturing and melt processing. The generation of third order intermodulation (IMD) products was observed at elevated if power levels. Correlation between IMDlevel and if field dependence of surface impedance is demonstrated. The contribution of grain boundaries to IMD is discussed in terms of the resistively shunted junction model.

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“…The presence of weak-links in granular material can give rise to diverse dependence of surface resistance upon microwave magnetic field. In this context, weak links are usually modeled in terms of the resistively shunted junction (RSJ) model [1,2,3,4,5,6]. Oates et al performed a control experiment using a stripline resonator geometry with an edge junction and found that the weak link followed an RSJ type behaviour [7].…”

Section: Introductionmentioning

confidence: 99%

The microwave power handling of an FIB-generated weak link in a YBCO film

Cowie

Cohen

Denhoff

1999

Supercond. Sci. Technol.

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Abstract. We have measured the power dependent microwave properties of a weak link in a YBa 2 Cu 3 O 7−δ thin film formed by writing a line of damage using a focused ion beam. The measurement was made using a parallel plate resonator at 5.5 GHz with the weak link written across the width of one of the plates. The ion induced damage was characterized using a TRIM computer simulation and the dc properties of similar weak links was measured. Using a 200 eV Si ion dose of 2 × 10 13 cm −2 , the T c of the damaged region was reduced by 5.5 K and the normal resistivity was doubled. Surprisingly, the microwave measurements did not show any Josephson junction characteristics. Rather, the ion damaged region exhibited a greatly increased microwave resistivity that was constant as a function of microwave power up to rf fields of 20 mT at 21 K.

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Microwave power-induced flux penetration and loss in high-temperature superconductors

Cited by 29 publications

References 46 publications

The flux-line lattice in superconductors

The flux-line lattice in superconductors

Generation of intermodulation products by granular YBa 2 Cu 3 O 7-x thick films

The microwave power handling of an FIB-generated weak link in a YBCO film

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