Influence of the pseudogap on the thermal conductivity and the Lorenz number of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">YBa</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Cu</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mm

Minami, Hirofumi; Wittorff, V. W.; Yelland, E. A.; Cooper, J. R.; Changkang, Chen; Hodby, J.W.

doi:10.1103/physrevb.68.220503

Cited by 21 publications

(17 citation statements)

References 17 publications

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“…For example, a-direction thermal conductivity on YBCO6+x was reported by Minami et al (24), but for similar doping, their crystals show much larger resistivity than measurements done on crystals similar to our crystals (12). At the same time, Inyushkin et al (40) measured twinned crystals with similar doping levels, which are expected to yield a larger value as the a-and b-directions average (50).…”

Section: Significancementioning

confidence: 74%

Anomalous thermal diffusivity in underdoped YBa ₂ Cu ₃ O _6+x

Zhang

Levenson-Falk

Ramshaw

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The thermal diffusivity in the ab plane of underdoped YBCO crystals is measured by means of a local optical technique in the temperature range of 25-300 K. The phase delay between a point heat source and a set of detection points around it allows for high-resolution measurement of the thermal diffusivity and its in-plane anisotropy. Although the magnitude of the diffusivity may suggest that it originates from phonons, its anisotropy is comparable with reported values of the electrical resistivity anisotropy. Furthermore, the anisotropy drops sharply below the charge order transition, again similar to the electrical resistivity anisotropy. Both of these observations suggest that the thermal diffusivity has pronounced electronic as well as phononic character. At the same time, the small electrical and thermal conductivities at high temperatures imply that neither well-defined electron nor phonon quasiparticles are present in this material. We interpret our results through a strongly interacting incoherent electron-phonon "soup" picture characterized by a diffusion constant D ∼ v 2 B τ , where v B is the soup velocity, and scattering of both electrons and phonons saturates a quantum thermal relaxation time τ ∼ /k B T.thermal diffusivity | bad metals | electron-phonon T he standard paradigm for transport in metals relies on the existence of quasiparticles. Electronic quasiparticles conduct electricity and heat. Phonon quasiparticles, the collective excitations of the elastic solid (here, we discuss acoustic phonons) also conduct heat. Transport coefficients, such as electrical and thermal conductivities, can then be calculated using, for example, Boltzmann equations (1). However, such an approach fails when the quasiparticle mean free paths become comparable with the quasiparticle wavelength. For electrons, it is the Fermi wavelength (2-4), whereas for phonons, it is the larger of the interatomic distance or minimum excited phonon wavelength (5, 6). Understanding transport in nonquasiparticle regimes requires a new framework and has become a subject of intense theoretical effort in recent years, triggering an urgent need for experimental results that can shed light on such regimes. In particular, in ref. 7, the diffusivity was singled out as a key observable for incoherent nonquasiparticle transport, possibly subject to fundamental quantum mechanical bounds.In this work, we report high-resolution measurements of the thermal diffusivity of single-crystal underdoped YBCO6.60 (an ortho-II YBa2Cu3O6.60) and YBCO6.75 (an ortho-III YBa2Cu3O6.75). We are particularly interested in the anisotropy of the thermal diffusivity as measured along the principal axes a and b (which is the chain direction) in the temperature range 25-300 K. We use a noncontact optical microscope (see Fig. S1) to perform local thermal transport measurements on the scale of ∼10 µm, hence avoiding inhomogeneities, particularly twinning and grain boundary effects. Our principal experimental results are as follows. (i) The measured thermal diffusivity is...

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Section: Significancementioning

confidence: 74%

Anomalous thermal diffusivity in underdoped YBa ₂ Cu ₃ O _6+x

Zhang

Levenson-Falk

Ramshaw

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…However, the usefulness of WF law is restricted by the fact that κ el is often only a small fraction of the total thermal conductivity and, moreover, there are circumstances in which the Lorenz number is no longer equal to L 0 . The most trivial reason is inelastic scattering of charge carriers by phonons that reduces value of L , another is a pseudogap, which emerges in the normal state of some unconventional superconductors , which causes an enhancement of L above L 0 . A very small Fermi energy will also cause an increase of L .…”

Section: Resultsmentioning

confidence: 99%

“…However, κ xy / BT < L 0 σ xy / B in Se15, whereas κ xy / BT > L 0 σ xy / B in Se41. Analogously to other transport coefficients, the total Hall–Lorenz number in a multiband conductor can be divided between hole and electron contributions as :

L_{x y} = \frac{L_{x y}^{normale} σ_{x y}^{normale} + L_{x y}^{normalh} σ_{x y}^{normalh}}{σ_{x y}^{normale} + σ_{x y}^{normalh}} .

…”

Section: Resultsmentioning

confidence: 99%

Wiedemann-Franz law in iron-based superconductor Fe_1+dTe_1−xSe_x

Matusiak

Babij

Pomjakushina

et al. 2016

Phys. Status Solidi B

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We present results of measurements of the transport phenomena in the series of Fe1+dTe1−xSex single crystals. Namely, we investigate the longitudinal and transverse electrical and thermal conductivities in the parent compound Fe1+dTe as well as superconducting Fe1+dTe0.85Se0.15 and Fe1+dTe0.59Se0.41. This set of data allows us to verify validity of the Wiedemann–Franz law in the systems studied and consequently it is stated that the electronic system in the paramagnetic phase of Fe1+dTe behaves like the Fermi liquid being predominantly elastically scattered. In contrast, low temperature properties of Fe1+dTe0.85Se0.15 and Fe1+dTe0.59Se0.41 are affected likely by the emergence of antiferromagnetic fluctuations, which are expected to be (π,0) and (π,π), respectively. These seem to be coupled with the hole‐like band in case of Fe1+dTe0.85Se0.15, whereas with the electron‐like band in case of Fe1+dTe0.59Se0.41.

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“…In addition to potentially scattering electrons, phonons in unconventional metals are unconventional in their own right, as was noted early on by [58]. Furthermore, the large Lorenz ratio of cuprates at high temperatures suggests that phonons play an important role in heat transport in these materials [58][59][60][61][62]. This stands in contrast to standard metals, in which heat is mostly carried by electrons, and is possible because in correlated systems the lower Fermi velocities reduce the electronic contribution to heat transport.…”

Section: Heat Transport and Planckian Phononsmentioning

confidence: 98%

Planckian Dissipation in Metals

Hartnoll,

Mackenzie

2021

Preprint

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We review the appearance of the Planckian time τ Pl = /(k B T ) in both conventional and unconventional metals. We give a pedagogical discussion of the various different timescales (quasiparticle, transport, many-body) that characterize metals, emphasizing conditions under which these times are the same or different. Throughout, we have attempted to clear up aspects of the problem that had been confusing us, in the hope that this helps the reader as well. We discuss the possibility of a Planckian bound on dissipation from both a quasiparticle and a many-body perspective. Planckian quasiparticles can arise naturally from a combination of inelastic scattering and mass renormalization.Many-body dynamics, on the other hand, is constrained by the basic time-and lengthscales of local thermalization.

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Influence of the pseudogap on the thermal conductivity and the Lorenz number ofYBa2Cu3O

Cited by 21 publications

References 17 publications

Anomalous thermal diffusivity in underdoped YBa ₂ Cu ₃ O _6+x

Anomalous thermal diffusivity in underdoped YBa ₂ Cu ₃ O _6+x

Wiedemann-Franz law in iron-based superconductor Fe_1+dTe_1−xSe_x

Planckian Dissipation in Metals

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Influence of the pseudogap on the thermal conductivity and the Lorenz number ofYBa2Cu3O

Cited by 21 publications

References 17 publications

Anomalous thermal diffusivity in underdoped YBa 2 Cu 3 O 6+x

Anomalous thermal diffusivity in underdoped YBa 2 Cu 3 O 6+x

Wiedemann-Franz law in iron-based superconductor Fe1+dTe1−xSex

Planckian Dissipation in Metals

Contact Info

Product

Resources

About

Anomalous thermal diffusivity in underdoped YBa ₂ Cu ₃ O _6+x

Anomalous thermal diffusivity in underdoped YBa ₂ Cu ₃ O _6+x

Wiedemann-Franz law in iron-based superconductor Fe_1+dTe_1−xSe_x