Contribution of electronic structure to elastic anomalies in metallic superlattices

Chang, Jianlin; Stott, M. J.

doi:10.1103/physrevb.46.10423

Cited by 12 publications

(5 citation statements)

References 46 publications

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“…In this way, with only four free parameters, we succeeded in fitting almost all of our data. Consulting other reports [1][2][3][4][5]7], we find that our quasiparticle DOS should be widely applicable. The fits are not as good for the double-peaked spectrum in YBCO, as in the inset in fig.…”

supporting

confidence: 72%

“…The superconducting DOS in BSCCO was studied in this work in both single crystals and thin films and found to be very similar. Furthermore, the tunneling spectra previously reported in BSCCO single crystals have the same form [1][2][3][4][5]. The spectrum presented as an example in fig.…”

mentioning

confidence: 77%

“…Using such a local probe at low temperature, reproducible vacuum tunneling spectra have been obtained on many cuprates [1][2][3][4][5][6][7][8], in particular Bi 2 Sr 2 CaCu 2 O 8+δ (BSCCO) and YBa 2 Cu 3 O 7 (YBCO). However, one still cannot interpret the experimental curves precisely.…”

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confidence: 99%

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Constraints on the quasiparticle density of states in high- T _c superconductors

et al. 2000

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In this Letter we present new tunneling data on YBa2Cu3O7 thin films by low temperature scanning tunneling spectroscopy. Unusual peak-dip-hump features, previously reported in Bi2Sr2CaCu2O 8+δ , are also found in YBa2Cu3O7. To analyse these common signatures we propose a new heuristic model in which, in addition to the d-wave symmetry, the gap function is energy dependent. A simple expression for the quasiparticle density of states is derived, giving an excellent agreement with the experiment. The dynamics of the quasiparticle states and the energy scales involved in the superconducting transition are discussed.Getting to the heart of the quasiparticle density of states (DOS) in cuprate superconductors is an active goal of current theoretical and experimental research. Indeed, in the case of conventional materials, the quasiparticle DOS in the superconducting state contains the key information on the pairing. For this reason various methods, such as angle-resolved photoemission (ARPES), tunneling (TS) and Raman spectroscopies, as well as optical conductivity, are extensively used to elucidate the pairing mechanism in cuprates. Among these, scanning tunneling spectroscopy (STS), with its high spatial and energy resolution, emerges as the technique of choice.Using such a local probe at low temperature, reproducible vacuum tunneling spectra have been obtained on many cuprates [1][2][3][4][5][6][7][8], in particular Bi 2 Sr 2 CaCu 2 O 8+δ (BSCCO) and YBa 2 Cu 3 O 7 (YBCO). However, one still cannot interpret the experimental curves precisely. The shape of the DOS in BSCCO has a non-trivial dependence on doping [7,9,10], temperature [7,[9][10][11][12][13][14][15][16] and magnetic field [17,18]. The state density is characterized by its large value at the Fermi level, unusual quasiparticle peaks and dip-hump structures at higher energies (see Fig.1). While the T c vs doping curve is bell-shaped, the gap width decreases linearly, as the doping increases from underdoped to overdoped regimes, with no significant change in the DOS shape [7,9,10]. The temperature dependence is also unconventional: The gap does not vanish at the critical temperature and a pseudogap persists at T > T c [7,9,[12][13][14][15]. Finally, a low temperature pseudogap remains when the superconducting order is destroyed, within the vortex core [18], or due to disorder [6]. All these features are difficult to explain with a BCS-type theory.In this Letter we report our new low-temperature STS data on YBCO thin films. We observe strongly pronounced peak-dip-hump structures and a significant state density at zero bias. With previous data on BSCCO, our observations suggest a common mechanism for these features, linked to the superconducting state in cuprates. In order to clarify this effect, we propose a new quasiparticle DOS based on an energy-dependent gap function. A particular form for this function is inferred from the data and has, in addition to d-wave symmetry, a single minimum at a characteristic energy near the gap value. Using such a simple ap...

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confidence: 77%

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Constraints on the quasiparticle density of states in high- T _c superconductors

et al. 2000

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“…As demonstrated in, 22 such a difference cannot be due to electronic effects. So, the presence of impurities with an atomic volume stronger than the tungsten one and interstitial defects are the only reasons able to explain this phenomenon.…”

Section: A Resultsmentioning

confidence: 90%

Residual stresses and microstructure in tungsten thin films analyzed by x-ray diffraction-evolution under ion irradiation

Durand

Badawi

Goudeau

1996

Journal of Applied Physics

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“…[6][7][8][9][10] Explanations for these effects have been given in terms of coherency strains, 11 electronic effects due to the folding of the Brillouin zone in the superlattice growth direction, 12 microstructural properties such as changes in the interlayer distances, 13 and effects of disordered interfaces. 14 It has been demonstrated, within specific models for the shape of the Fermi surface, 15 that the Brillouin-zone effects give no significant contributions to the elastic moduli. The same conclusion was drawn in a first-principles calculation of elastic properties of Au/Cr superlattices with respect to modulation wavelength.…”

Section: Introductionmentioning

confidence: 99%

Elastic constants of Mo/V superlattices

Papadia-Einarsson

1997

Phys. Rev. B

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Elastic moduli of Mo, V, and Mo n /V n superlattices with nр3 are calculated in the full-potential linear muffin-tin orbital scheme. No modulation dependence is found for the bulk modulus of the superlattices. Comparisons are made with predictions from continuum models for elastic moduli of layered materials and surprising agreement is found between those and the calculated constants. In the context of elastic anomalies frequently observed for metal superlattices, an estimation employing the Hashin-Shtrikman bounds for composites gives that a softening of Young's modulus up to 30% would be obtained if the disorder at the interfaces were extreme. This suggests that the frequently observed elastic anomalies for small-modulation superlattices is intimately connected with the quality of the interfaces.

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Contribution of electronic structure to elastic anomalies in metallic superlattices

Cited by 12 publications

References 46 publications

Constraints on the quasiparticle density of states in high- T _c superconductors

Constraints on the quasiparticle density of states in high- T _c superconductors

Residual stresses and microstructure in tungsten thin films analyzed by x-ray diffraction-evolution under ion irradiation

Elastic constants of Mo/V superlattices

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Contribution of electronic structure to elastic anomalies in metallic superlattices

Cited by 12 publications

References 46 publications

Constraints on the quasiparticle density of states in high- T c superconductors

Constraints on the quasiparticle density of states in high- T c superconductors

Residual stresses and microstructure in tungsten thin films analyzed by x-ray diffraction-evolution under ion irradiation

Elastic constants of Mo/V superlattices

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Product

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Constraints on the quasiparticle density of states in high- T _c superconductors

Constraints on the quasiparticle density of states in high- T _c superconductors