The field dependence of the thermal conductivity: Evidence for nodes in the gap

Salamon, M. B.; Fang, Yu; Kopylov, V. N.

doi:10.1007/bf00722827

Cited by 40 publications

(29 citation statements)

References 8 publications

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“…Perhaps this is due to the fact there is more quasi-particle for θ = 0 than for θ = ± On the other hand, the transverse thermal conductivity is described by κ ⊥ ∼ −H sin(2θ) in the both limits. This dependence appears to describe quite well the data reported in [11,12]. For simplicity, we limit our analysis to T ≪ T c and H ≪ H c2 and the impurity scattering is treated in the unitarity limit.…”

Section: 23supporting

confidence: 54%

Quasi-particle transport in vortex state of nodal superconductors

Won

Maki

2001

Current Applied Physics

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Quasiparticle spectrum associated with the nodal structure in d-wave superconductors is of great interest. We study theoretically the quasi-particle spectrum in a planar magnetic field, where the effect of the magnetic field is treated in terms of the Doppler shift. We obtain the angular dependent specific heat in the presence of a planar magnetic field and impurities, both in the superclean limit(≪ 1) and in the clean limit(. Also a similar analysis is used for the thermal conductivity tensor within the a-b plane. In particular, in contrast to the earlier works, we find a fourfold symmetry term in κ and κ ⊥ ∼ −H sin(2θ) where κ and κ ⊥ are the diagonal-and the off-diagonal components of the thermal conductivity tensor and θ is the angle between the heat current and the magnetic field.

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Section: 23supporting

confidence: 54%

Quasi-particle transport in vortex state of nodal superconductors

Won

Maki

2001

Current Applied Physics

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“…We dedicate this article to Prof. Dr. E. Müller-Hartmann on the occasion of his 60th birthday a e-mail: freimuth@ph2.uni-koeln.de b Present address: Walther-Meissner Institute for Low Temperature Research, Bavarian Academy of Sciences, 85748 Garching, Germany A characteristic feature of YBa 2 Cu 3 O 7−δ close to optimum doping is a pronounced maximum of the thermal conductivity in the superconducting state [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The position and the height of this maximum depend strongly on the sample quality and it is suppressed by a magnetic field [3][4][5]10,14].…”

Section: Introductionmentioning

confidence: 99%

“…The position and the height of this maximum depend strongly on the sample quality and it is suppressed by a magnetic field [3][4][5]10,14]. 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].…”

Section: Introductionmentioning

confidence: 99%

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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“…Unlike gapless superconductivity, which can occur in conventional superconductors, the Fermi momenta of these quasiparticles are restricted to nodal regions of the Fermi surface, giving a strong directional dependence to various physical properties. While pioneering work by Salamon and coworkers [1,2] and by subsequent experimenters [3,4] demonstrated the directionality of thermally excited nqp's via the thermal conductivity, direct detection has proven elusive.…”

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confidence: 99%

Evidence for Nodal Quasiparticles in the Nonmagnetic SuperconductorYNi2B2Cvia Field-Angle-Dependent Heat Capacity

et al. 2003

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Field-angle dependent heat capacity of the non-magnetic borocarbide superconductor YNi 2 B 2 C reveals a clear fourfold oscillation, the first observation of its kind. The observed angular variations were analyzed as a function of magnetic field angle, field intensity and temperature to provide its origin. The quantitative agreement between experiment and theory strongly suggests that we are directly observing nodal quasiparticles generated along < 100 > by the Doppler effect. The results demonstrate that field-angle heat capacity can be a powerful tool in probing the momentumspace gap structure in unconventional superconductors such as high T c cuprates, heavy fermion superconductors, etc.

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The field dependence of the thermal conductivity: Evidence for nodes in the gap

Cited by 40 publications

References 8 publications

Quasi-particle transport in vortex state of nodal superconductors

Quasi-particle transport in vortex state of nodal superconductors

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

Evidence for Nodal Quasiparticles in the Nonmagnetic SuperconductorYNi2B2Cvia Field-Angle-Dependent Heat Capacity

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