Model for<i>c</i>-axis transport in high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="italic">T</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="italic">c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>cuprates

Rojo, A. G.; Levin, K.

doi:10.1103/physrevb.48.16861

Cited by 102 publications

(102 citation statements)

References 9 publications

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“…For difise pair transport (parallel momentum not conserved [17,18,19], the Josephson current densily between two identical superconducting sheets at T=O is given by J. = zAO/2eR~ [20], where AO is the zero temperature energy gap, and RL is the nornud state resistance per plane perpendicular~othe planes.…”

Section: A Survey Of Our Images Of Interlayer Vortices In Several Supmentioning

confidence: 99%

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: A Survey Of Our Images Of Interlayer Vortices In Several Supmentioning

confidence: 99%

Magnetic imaging of interlayer Josephson vortices

Kirtley

Moler

Schlueter

et al. 1999

Advances in Superconductivity XI

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“…The temperature dependence is introduced either phenomenologically 29 , 30 or through thermal occupation of electron states in the conducting layers 9,31,32 , or else, as it was done in the short version of this paper 17 , through a phonon-assisted tunneling. Whether inter-plane disorder is the reason for the anomalous c-axis transport in all layered materials is not clear at the moment.…”

Section: Introductionmentioning

confidence: 99%

“…Transport of these states is described by the Boltzmann conductivity σ B c which has a metallic temperature dependence. As resonant tunneling opens a new channel of conduction, the total conductivity can be described by a phenomenological formula 7,30,34 …”

Section: Introductionmentioning

confidence: 99%

Boson-assisted tunneling in layered metals

Gutman

Maslov

2008

Phys. Rev. B

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“…0 1997 Elsevier Science Ltd. All rights reserved Recently, much attention [l-6] has been paid to the study of the localization transition in anisotropic materials. It seems now that there is general agreement that the critical disorder at which the localization transition takes place and the critical exponent of the localization length are independent of the direction of measurement in spite of the anisotropy.On the other hand, a careful study by way of a fully 3-dimensional (3D) model is necessary for disordered superlattice (SL) system, where most theoretical studies [7] are based upon l-dimensional (1D) models. In an ideal SL, i.e.…”

mentioning

confidence: 99%

“…On the other hand, a careful study by way of a fully 3-dimensional (3D) model is necessary for disordered superlattice (SL) system, where most theoretical studies [7] are based upon l-dimensional (1D) models. In an ideal SL, i.e.…”

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confidence: 99%

A study of localization in a model superlattice with 3-dimensional disorder distribution

Song

Kim

1997

Solid State Communications

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We study a microscopic model for a disordered superlattice system, which simulates the effect of intrinsic alloy fluctuation on localization in alloy superlattices. Numerical investigation of scaling behavior of the localization length shows that excitations along and perpendicular to the superlattice axis undergo a localization transition at a nonzero critical disorder. Therefore, we contend that for localization, the alloy superlattices should be viewed as a 3-dimensional anisotropic material. At the transition, the localization length diverges with critical exponent v = 1.2 t 0.2. We expect that the model belongs to the same universality class as the 3 dimensional isotropic Anderson model. 0 1997 Elsevier Science Ltd. All rights reserved Recently, much attention [l-6] has been paid to the study of the localization transition in anisotropic materials. It seems now that there is general agreement that the critical disorder at which the localization transition takes place and the critical exponent of the localization length are independent of the direction of measurement in spite of the anisotropy.On the other hand, a careful study by way of a fully 3-dimensional (3D) model is necessary for disordered superlattice (SL) system, where most theoretical studies [7] are based upon l-dimensional (1D) models. In an ideal SL, i.e. no disorder present, the excitation along the SL axis is decoupled from those in other directions so that it is essentially described by 1D equations of motion. Almost all electronic and vibrational excitations are known to be localized in 1D space at any nonzero disorder [8,9]. Since a certain degree of disorder is always present in real SLs, localization of any excitation is inevitable in the 1D pictures of SL. However, on the experimental side, it has been shown [lo] that Bloch transport along the SL axis can take place for relatively small alloy concentration. Moreover, it has been shown [ 1 l] that there exists a confined-to-propagating transition of GaAs optical phonons and low energy electronic excitations in GaAs/Al,Gai_,As SL as the alloy concentration x is varied. These experimental findings cast doubt on the 1D pictures of SL in the presence of disorder and suggest that for localization disordered SLs should be considered as a 3D anisotropic material. The impurities in real SL cannot be taken into account fully within 1D models since disorder effects arise not only from randomness along the SL axis but also from the fact that impurities exist in the form of the in-plane (parallel to the SL layers) randomness. In the presence of 3-dimensional (3D) disorder, the three spatial components of an excitation are coupled with one another and the equations of motion do not reduce to 1D ones. A more interesting but rarely investigated case involving the in-plane randomness is the alloy SLs, e.g. GaAs/Al,Gal_,As.A disorder normally considered in the GaAs/Al,Gat_,As system is the well-width fluctuation, which is dealt with in 1D picture. The intrinsic alloy disorder cannot be properly treated ...

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Model forc-axis transport in high-Tccuprates

Cited by 102 publications

References 9 publications

Magnetic imaging of interlayer Josephson vortices

Magnetic imaging of interlayer Josephson vortices

Boson-assisted tunneling in layered metals

A study of localization in a model superlattice with 3-dimensional disorder distribution

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