Global and local measures of the intrinsic Josephson coupling in Tl2Ba2CuO6 as a test of the interlayer tunnelling model

Tsvetkov, A. Yu.; Marel, D. van der; Moler, Kathryn A.; Kirtley, J. R.; Boer, J. L. de; Meetsma, Auke; Ren, Zhifeng; Koleshnikov, N.; Dulić, Diana; Damascelli, A.; Grüninger, M.; Schützmann, J.; Eb, J. W. van der; Somal, H. S.; Wang, J. H.

doi:10.1038/26439

Cited by 114 publications

(83 citation statements)

References 9 publications

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“…is a source for conce~as one could imagine that vortices trap in regions with exceptionally weak, interpIane coupling, so that our measurements might overestimate the intrinsic penetration depths. However, measurements of the Josephson plasma resonance, which average eve; large regions of the sample, are in good agreement with our measurements for T1-2201 [15]. .…”

Section: Disclaimersupporting

confidence: 89%

Magnetic imaging of interlayer Josephson vortices

Kirtley

Moler

Schlueter

et al. 1999

Advances in Superconductivity XI

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We have magnetically imaged interlayer Josephson vortices emergin %!!?g% planes of single crystals of the organic superconductor~-(BEDT-TTF)z CU(N 5 single layer cuprate high-T~superconductors TkBazCuOcti (TI-2201) and (Hg,Cu Bz@u( Hg-1201), using a scanning Superconducting Quantum Interference Device (@I@ microscope. These images provide a direct measurement of the interIayer penetration deptw hich is approximately 63pm for~-(BEDT-TTF)z CU(NCS)Z, 18~m for T1-2201 and 8pm for Hg-1201. The lengths for the cuprates are about a factor of 10 larger than originally pre&cted by the interlayer tunneling model for the mechanism of superconductivity in layered compounds, irdcating that thk mechanism alone cannot account for the high critical temperatures in these materials. .Key words: interlayer, vortex, SQUID, magnetic, microscopy Many unconventional superconductors, notably cuprates and some organics, have a strongly anisotropic layered structure. The layered superconductors are commonly modekd using the Lawrence-Doniach model [l], as a stack of "conventional" superconducting layers with Josephson coupliig beh.veen the layers. The strength of the interlayer coupling is an important partieter in any phenomenological description of these materials, but it can be difllcult to measure. We discuss in this paper a duect way to measure this interlayer couplin~by imaging vortices trapped parallel to, and screened by, the superconducting layers. The magneti? "shape" of these vortices is directly related to the strength of the interlayer coupling, through the interlayer penetration depth lL=(c0J8z%J0 )ln [2], where JOis tie interlayer critical current density, c is the speed of Iigh$ @O =hd2e is the superconducting flux quanu h is Planck's constan; e is the charge on the electro~and s is the interlayer spacing. Clem and Coffey derived expressions for the structure of vortices parallel to the layers (Fig. la), called "interlayer Josephson vortices", in the context of the Lawrence-Doniach mode1 [2]. Except at the smalkst length scales, these vortices are identical to vortices in an anisotropic London model. Kogan and Clem [3] calculated the magnetic fields from an anisotropic vortex extending above a superconducting surface. By comparing these expression with our measurements, we get quantitative values for the interlayer penetration depths.~T

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Section: Disclaimersupporting

confidence: 89%

Magnetic imaging of interlayer Josephson vortices

Kirtley

Moler

Schlueter

et al. 1999

Advances in Superconductivity XI

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“…These and other findings have led to the conclusion that the out-of-plane transport in these crystals is incoherent. [2][3][4][5][6][7] The microscopic models based on the assumption of incoherence of the c-axis transport such as that in Ref. 8 and others 1,2 corroborate this conjecture, because the properties of c obtained within these models reproduce some of the features of the real systems.…”

Section: Introductionsupporting

confidence: 65%

Phenomenology of conduction in incoherent layered crystals

Levin¹

2004

Phys. Rev. B

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A novel phenomenological approach to the analysis of the conductivities of incoherent layered crystals is presented. It is based on the fundamental relationship between the resistive anisotropy σ ab /σc and the ratio of the phase coherence lengths in the respective directions. We explore the model-independent consequences of a general assumption that the out-of-plane phase coherence length of single electrons is a short fixed distance of the order of interlayer spacing. Several topics are discussed: application of the scaling theory, magnetoresistivity, the effects of substitutions and the intermediate regime of conduction when both coherence lengths change with temperature, but at different rate.

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“…The agreement in LSCO seems quite good, 6,4 but experiments on Hg-1201 7 and Tl-2201 8,9,10 give estimates for λ c which are 8-20 times larger than the predicted values. 4 However, note that Chakravarty et al 11 have argued that this discrepancy between theory and experiment can be drastically reduced by taking more carefully into account the fluctuation contributions to the normal state specific heat when estimating E cond .…”

Section: Introductionmentioning

confidence: 88%

Non-k-Diagonality in the Interlayer Pair-Tunneling Model of High-Temperature Superconductivity

sgmaelig

restad

Sudbø³

1999

Journal of Low Temperature Physics

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We investigate the effect of k-space broadening of the interlayer pairing kernel on the critical temperature Tc and the k-dependence of the gap function in a one-dimensional version of the interlayer pair-tunneling model of high-Tc superconductivity. We consider constant as well as k-dependent intralayer pairing kernels. We find that the sensitivity to k-space broadening is larger the smaller the width of the peak of the Fermi-level gap calculated for zero broadening. This width increases with the overall magnitude of the interlayer tunneling matrix element, and decreases with the bandwidth of the single-electron intralayer excitation spectrum. The width also increases as the Fermi level is moved towards regions where the excitation spectrum flattens out. We argue that our qualitative conclusions are valid also for a two-dimensional model. This indicates that at or close to half-filling in two dimensions, when the Fermi-surface gap for zero broadening attains its peaks at (±π/a, 0) and (0, ±π/a) where the excitation spectrum is flat, these peaks should be fairly robust to moderate momentum broadening.

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Global and local measures of the intrinsic Josephson coupling in Tl2Ba2CuO6 as a test of the interlayer tunnelling model

Cited by 114 publications

References 9 publications

Magnetic imaging of interlayer Josephson vortices

Magnetic imaging of interlayer Josephson vortices

Phenomenology of conduction in incoherent layered crystals

Non-k-Diagonality in the Interlayer Pair-Tunneling Model of High-Temperature Superconductivity

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