Microwave Surface Impedance of High Temperature Superconductors

Bonn, D. A.; Hardy, W. N.

doi:10.1142/9789814261289_0002

Cited by 53 publications

(77 citation statements)

References 81 publications

(122 reference statements)

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“…The interpretation of this behavior in terms of QP-dynamics requires a drastic suppression of the QP-scattering rate below T c , which overcompensates the decrease of the number of QPs [7]. Such a behavior of the scattering rate has been inferred earlier from the microwave surface resistance [15][16][17][18][19]. It provides strong evidence for an electronic origin of the scattering processes in the cuprates.…”

Section: Introductionmentioning

confidence: 67%

“…(Compare, however, Eq. (15) and the corresponding discussion.) In the superconducting state both methods to determine k el xx cannot be used in a straightforward way.…”

Section: Wiedemann-franz Lawmentioning

confidence: 90%

“…In this case the Lorenz numbers are usually temperature dependent. It has been pointed out in reference [30] that the temperature dependencies of L xx and L xy may be different so that L xx (T ) and L xy (T ) do not cancel in equation (15). For example, inelastic scattering processes give different mean-free paths for the entropy ( S ) and charge ( e ) currents.…”

Section: Test Measurements On Niobiummentioning

confidence: 99%

“…To obtain σ xx the superfluid response to electric fields must be separated from that of the QPs, which requires a (model dependent) analysis [15]. Moreover, the Wiedemann-Franz law itself is not necessarily fulfilled in the superconducting state even for elastic scattering [20].…”

Section: Wiedemann-franz Lawmentioning

confidence: 99%

“…k el xx = LT σ xx , where L is the Lorenz-number. However, in the superconducting state this requires a (model dependent) determination of the QP-contribution to σ xx from the combined superfluid and QP-response to electric fields [15]. Moreover, in contrast to the normal state, in a superconductor L may be temperature dependent even for purely elastic scattering, as a consequence of different coherence factors for electrical and thermal transport effects [20].…”

Section: Introductionmentioning

confidence: 99%

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Thermal conductivity and thermal Hall effect in Bi- and Y-based high-T c superconductors

et al. 2001

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Measurements of the thermal conductivity (kxx) and the thermal Hall effect (kxy) in high magnetic fields in Y-and Bi-based high-Tc superconductors are presented. We describe the experimental technique and test measurements on a simple metal (niobium). In the high-Tc superconductors kxx and kxy increase below Tc and show a maximum in their temperature dependence. kxx has contributions from phonons and quasiparticle (QP) excitations, whereas kxy is purely electronic. The strong increase of kxy below Tc gives direct evidence for a strong enhancement of the QP contribution to the heat current and thus for a strong increase of the QP mean free path. Using kxy and the magnetic field dependence of kxx we separate the electronic thermal conductivity (k el xx ) of the CuO2-planes from the phononic thermal conductivity (k ph xx ). In YBa2Cu3O 7−δ k el xx shows a pronounced maximum in the superconducting state. This maximum is much weaker in Bi2Sr2CaCu2O 8+δ , due to stronger impurity scattering. The maximum of k el xx is strongly suppressed by a magnetic field, which we attribute to the scattering of QPs on vortices. An additional magnetic field independent contribution to the maximum of kxx occurs in YBa2Cu3O 7−δ , reminiscent of the contribution of the CuO-chains, as determined from the anisotropy in untwined single crystals. Our data analysis reveals that below Tc as in the normal state a transport (τ ) and a Hall (τH) relaxation time must be distinguished: The inelastic (i.e. temperature dependent) contribution to τ is strongly enhanced in the superconducting state, whereas τH displays the same temperature dependence as above Tc. We determine also the electronic thermal conductivity in the normal state from kxy and the electrical Hall angle. It shows an unusual linear increase with temperature.

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Section: Introductionmentioning

confidence: 67%

“…(Compare, however, Eq. (15) and the corresponding discussion.) In the superconducting state both methods to determine k el xx cannot be used in a straightforward way.…”

Section: Wiedemann-franz Lawmentioning

confidence: 90%