Elastic constants of a monocrystal of superconducting<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:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><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:math><mm

Lei, Ming; Sarrao, J. L.; Visscher, William M.; Bell, Thomas M.; Thompson, J. D.; Migliori, A.; Welp, U.; Veal, B. W.

doi:10.1103/physrevb.47.6154

Cited by 125 publications

(63 citation statements)

References 14 publications

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“…Assuming that the highest-frequency phonon excited at RT is proportional to temperature, the corresponding minimum phonon wavelength is λmin ∼ hvs /kB T . The sound velocities of a similar YBCO6.60 crystal have been measured, yielding v a s = 6.0 × 10 3 and v b s = 6.5 × 10 3 m/s (41). Shear sound velocity may be a factor ∼ √ 3 smaller, which does not change the following arguments.…”

Section: Significancementioning

confidence: 83%

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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: 83%

“…6 to fit the thermal diffusivity data. Literature values are used for the total specific heat (23), electronic specific heat (57), Fermi velocity (58), and sound velocities (41,65).…”

Section: Methodsmentioning

confidence: 99%

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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“…If both ⑀ a and ⑀ b are tensile, a compressive effect is expected in ⑀ c , according to the Poisson effect. An estimate can be done using the elastic moduli determined by Lei et al 18 (C ca ϭ89 GPa, C cb ϭ93 GPa, and C cc ϭ138 GPa). If we again assume that for the 1 unit cell YBCO sample ⑀ a and ⑀ b are those expected from the lattice mismatch to the PBCO, a value for the c lattice parameter of 11.51 Å is obtained, which is close enough to the 11.49 Å obtained from the x ray fits, if one keeps in mind that films show shorter c lattice parameters than bulk samples.…”

Section: Resultsmentioning

confidence: 99%

Epitaxial mismatch strain inYBa2Cu3O7−
Varela
¹
,
Arias
²
,
Sefrioui
³

et al. 2000
Phys. Rev. B
17
1
20
1
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The effects of epitaxial strain in ultrathin YBa 2 Cu 3 O 7Ϫ␦ layers have been investigated by x-ray diffraction and transmission electron microscopy. The samples used were high quality ͓YBa 2 Cu 3 O 7Ϫ␦ (YBCO) N / PrBa 2 Cu 3 O 7 (PBCO) M ͔ 1000 Å superlattices, grown by high oxygen pressure sputtering, with N ranging between 1 and 12 unit cells and M ϭ5 unit cells. Superlattice structure is refined by fitting x-ray spectra to a structural model containing disorder related parameters. Epitaxial mismatch strain and the absence of step disorder are found for YBCO layer thickness below 4 unit cells. A surprising reorganization of interatomic distances results, which seems to correlate with the decrease in the critical temperature. For larger YBCO layer thickness, stress relaxes and step disorder builds up. Transmission electron microscopy observations show the presence of a-axis orientated microdomains, which seem to be correlated to the release of epitaxial strain, provided in plane mismatch is smaller in this orientation.

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“…Later on, the method was significantly improved by Ohno and his coworkers, enabling determination of anisotropic elastic coefficients up to orthorhombic [3] and trigonal [4] symmetry class from measurements on a rectangular parallelepiped (so-called rectangular parallelepiped resonance, RPR). In early 1990s, Migliori et al [5] introduced this method to solid state physics community, and applied it immediately to in-situ monitoring of elasticity changes of high temperature superconductors when undergoing transitions to the superconducting state [6]. In these pioneering works, also the more general abbreviation RUS started to be used.…”

Section: Introductionmentioning

confidence: 99%

Resonant ultrasound spectroscopy for investigation of thin surface coatings

Seiner

Růžek

Sedlák

et al. 2009

Computational Methods and Experiments in Materials Characterisation IV

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In this paper, we analyze the possibility of determination of all in-plane independent elastic coefficients of an anisotropic surface coating on a known substrate by means of resonant ultrasound spectroscopy (RUS). A novel approach based on perturbation theory is presented, which enables direct determination of the elastic coefficients of the coating from the shift of resonant frequencies induced by the deposition of the layer. The reliability of the proposed concept is investigated by numerical simulations as well as verified by experiments.

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Elastic constants of a monocrystal of superconductingYBa2Cu3

Cited by 125 publications

References 14 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

Epitaxial mismatch strain inYBa2Cu3O7−
Varela
¹
,
Arias
²
,
Sefrioui
³

et al. 2000
Phys. Rev. B
17
1
20
1
View full text Add to dashboard Cite

Resonant ultrasound spectroscopy for investigation of thin surface coatings

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Elastic constants of a monocrystal of superconductingYBa2Cu3

Cited by 125 publications

References 14 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

Epitaxial mismatch strain inYBa2Cu3O7−Varela1, Arias2, Sefrioui3 et al. 2000Phys. Rev. B171201View full textAdd to dashboardCite

Resonant ultrasound spectroscopy for investigation of thin surface coatings

Contact Info

Product

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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

Epitaxial mismatch strain inYBa2Cu3O7−
Varela
¹
,
Arias
²
,
Sefrioui
³

et al. 2000
Phys. Rev. B
17
1
20
1
View full text Add to dashboard Cite