Pressure dependence of the electron-phonon interaction and the normal-state resistivity

We discuss the interpretation of measurements of thermal conductivity, thermopower, Hall coefficient, resistivity and mapetorcsistance in hiJh-temperaturc superconductors. The thermal conductivity of YBa2 Cu3 07 shows an increase below the transition temperature 7;:, demonstrating the importance of the electron-phonon interaction in reducing the phonon current in the normal state. Many features of resistivity and thermopower can be interpreted in terms of conventional metallic models, although morc exotic interpretations have been proposed. We show how measurements on morc disordered samples should help resolve controversy regarding the interpretation of the electronic transport properties.

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Far-Infrared Properties of ab plane oriented YBa2Cu3O7-δ

MRS Proceedings ◽

10.1557/proc-99-227 ◽

1987 ◽

Vol 99 ◽

Author(s):

D. A. Bonn ◽

A. H. O'Reilly ◽

J. E. Greedan ◽

C. V. Stager ◽

T. Timusk ◽

...

Keyword(s):

Transition Temperature ◽

Normal State ◽

Superconducting State ◽

Plasma Frequency ◽

Far Infrared ◽

Superconducting Transition ◽

Phonon Interaction ◽

Electron Phonon Interaction ◽

Oriented Samples ◽

Absolute Reflectance

ABSTRACTPolycrystalline samples of YBa2Cu2O7-δ with a variety of surface treatments show differences in absolute reflectance and width of phonon lines. Samples that are not polished and are measured immediately after annealing have largely grains with the c axis normal to the surface. Such oriented samples show a gap-like depression of conductivity in the far infrared that sets in below the superconducting transition temperature but no true gap. Phonon lines at 195 cm−1 and at 155 cm−1 narrow in the superconducting state, in analogy with the effect of the electron phonon interaction in BCS superconductors. In the normal state the background conductivity is Drude like with a plasma frequency of 0.75 eV and a relaxation rate of 200 cm−1. The extrapolated far-infrared conductivity agrees with the measured dc conductivity.

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Pressure dependence of Tc and electron phonon interaction in MBa2Cu3O7 systems

Journal de Physique ◽

10.1051/jphys:0198900500120143300 ◽

1989 ◽

Vol 50 (12) ◽

pp. 1433-1443 ◽

Cited By ~ 6

Author(s):

J.M. Besson

Keyword(s):

Pressure Dependence ◽

Phonon Interaction ◽

Electron Phonon Interaction

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Pressure dependence of the electron-phonon interaction of Sn and Zr

Solid State Communications ◽

10.1016/0038-1098(90)91005-2 ◽

1990 ◽

Vol 74 (12) ◽

pp. 1355-1358

Author(s):

J. Sjöström ◽

T. Jarlborg ◽

Ö. Rapp

Keyword(s):

Pressure Dependence ◽

Phonon Interaction ◽

Electron Phonon Interaction

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Absence of evidence of superconductivity in sulfur hydride in optical reflectance experiments

10.21203/rs.3.rs-967287/v1 ◽

2021 ◽

Author(s):

J. E. Hirsch ◽

F. Marsiglio

Keyword(s):

High Temperature ◽

Normal State ◽

High Temperature Superconductor ◽

Measured Data ◽

Superconducting Transition ◽

Phonon Interaction ◽

Optical Reflectance ◽

Electron Phonon Interaction ◽

Reflectance Measurements

Abstract Capitani and coworkers reported that infrared optical reflectance measurements provided evidence for a superconducting transition in sulfur hydride under 150 GPa pressure, and that the transition is driven by the electron-phonon interaction. Here we argue that the measured data did not provide evidence that the system undergoes a transition to a superconducting state, nor do the data support any role of phonons in driving a transition. Rather, the data are consistent with the system remaining in the normal state down to temperature 50K, the lowest temperature measured in the experiment. This calls into further question the generally accepted view that sulfur hydride under pressure is a high temperature superconductor.

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Temperature and pressure dependence of the electronic structure of tetracyanoquinodimethane crystals and the effect of impurities

Canadian Journal of Physics ◽

10.1139/p85-252 ◽

1985 ◽

Vol 63 (12) ◽

pp. 1513-1517 ◽

Cited By ~ 1

Author(s):

L. Roubi ◽

C. Cyr ◽

S. Desgreniers ◽

C. Carlone ◽

K. D. Truong ◽

...

Keyword(s):

Pressure Dependence ◽

Room Temperature ◽

Phonon Interaction ◽

Electron Phonon Interaction ◽

First Case ◽

Volume Dilatation ◽

Structural Differences ◽

Irreversible Effects ◽

Effect Of Impurities ◽

Temperature And Pressure

The absorption spectrum (12 500–32 260 cm−1) of tetracyanoquinodimethane crystals has been obtained at 0 bars in the [001] and [010] direction at 84 and 300 K. The peak of the Ag → Bu transition has been identified at 21 370 cm−1 and that of the Ag → Au transition at 22 000 cm−1. The change with temperature of both transitions was −3.4 ± 0.1 cm−1∙K−1. The [001] absorption was also obtained at room temperature as a function of the pressure, up to 5.0 × 104 bar, for crystals grown in two different laboratories, giving the change with pressure as −0.037 ± 0.003 and −0.092 ± 0.010 cm−1∙bar−1, respectively. At ambient temperature the explicit contribution, which is a measure of the electron–phonon interaction, was negative and dominated the temperature dependence. The implicit contribution, which is a measure of the volume dilatation, contributed in the opposite way, i.e., positively. Working at room temperature, we observed on both samples irreversible effects at higher pressures. In the first case, a discontinuous change occurred at (12 ± 1) × 103 bar, with new peaks appearing both at higher energy (25 600 cm−1) and lower energy (12 500 cm−1). In the second case, the absorption peak shifted continuously towards lower energies, but it broadened abruptly above 1.3 × 104 bar. We believe that the differences in the pressure dependence of the optical properties are due to the presence of small amounts of impurities in the samples causing subtle structural differences and that the irreversible effects are due to pressure-induced chemical changes.

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