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

Phonon Interaction ◽

Optical Reflectance ◽

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.

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 ◽

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.

Isotope Effect in the Translation-Invariant Bipolaron Theory of High-Temperature Superconductivity

Condensed Matter ◽

10.3390/condmat5040080 ◽

2020 ◽

Vol 5 (4) ◽

pp. 80

Author(s):

Victor D. Lakhno

Keyword(s):

High Temperature ◽

Isotope Effect ◽

High Temperature Superconductivity ◽

High Temperature Superconductors ◽

Strong Electron ◽

Translation Invariant ◽

Theory Of Superconductivity

It is shown that the translation-invariant bipolaron theory of superconductivity can explain the dependence of the isotope coefficient in high-temperature superconductors on the critical temperature of a superconducting transition: in the case of strong electron–phonon interaction, the isotope coefficient is low when doping is optimal and high when it is weak. It is demonstrated that in the case of London penetration depth, the absolute value of the isotope coefficient behaves in the opposite way. A conclusion of the great role of non-adiabaticity in the case of weak doping is made. The criteria for d-wave phonon input into the isotope effect is established.

ELECTRON-PHONON INTERACTION FOR AN ANALYTIC SOLUTION TO THE BCS EQUATION FOR THE HIGH TEMPERATURE SUPERCONDUCTORS

Modern Physics Letters B ◽

10.1142/s0217984991001647 ◽

1991 ◽

Vol 05 (20) ◽

pp. 1349-1353 ◽

Cited By ~ 2

Author(s):

H. C. GUPTA

Keyword(s):

High Temperature ◽

Transition Temperature ◽

Superconducting Transition Temperature ◽

Analytic Solution ◽

Energy Gap ◽

High Temperature Superconductors ◽

Phonon Interaction ◽

Gap Parameter

An energy dependent electron-phonon interaction has been used in the BCS equation. This provides an exactly solvable analytic solution to the BCS equation for the superconducting transition temperature and the gap parameter at absolute zero. These analytically obtained equations reduce to standard BCS form when temperature is small. These equations are applicable to low as well as high temperature superconductors successfully for their superconducting transition temperature and the energy gap parameter.

High-temperature superconductor thin-film characterization by the modulated optical reflectance technique

Superconductor Science and Technology ◽

10.1088/0953-2048/8/8/011 ◽

1995 ◽

Vol 8 (8) ◽

pp. 667-672 ◽

Cited By ~ 9

Author(s):

D P Almond ◽

A K Barker ◽

A C Bento ◽

S K Singh ◽

N J Appleyard ◽

...

Keyword(s):

Thin Film ◽

High Temperature ◽

High Temperature Superconductor ◽

Optical Reflectance ◽

Thin Film Characterization

The Gap and the Upper Critical FieldHc2as Function of Doping for High-TcCuprates

Advances in Condensed Matter Physics ◽

10.1155/2014/212895 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

S. Orozco ◽

R. M. Méndez-Moreno ◽

M. A. Ortiz

Keyword(s):

High Temperature ◽

Critical Field ◽

Energy Gap ◽

High Temperature Superconductors ◽

Upper Critical Field ◽

Superconducting Gap ◽

Phonon Interaction ◽

As Doping ◽

Wave Symmetry

The relation between thed-wave superconducting gapΔ0and the specific heat obtained with the Volovik effect is used to determine the upper critical fieldHc2as doping function, for high-temperature superconductors. A two-components model withd-wave symmetry, within the BCS framework, is introduced to describe the superconducting state. Generalized Fermi surface topologies are used in order to increase the density of states at the Fermi level, allowing the high-Tcvalues observed. The electron-phonon interaction is considered the most relevant mechanism for the high-Tccuprates, where the available phonon energy is provided by the half-breathing modes. The energy gap valuesΔ0calculated with this model are introduced to describe the variation of the upper critical fieldHc2as function of doping, forLa2-xSrxCuO4.

Phonons in ultrathin Bi(111) films: Role of spin-orbit coupling in electron-phonon interaction

Physical Review B ◽

10.1103/physrevb.87.075412 ◽

2013 ◽

Vol 87 (7) ◽

Cited By ~ 19

Author(s):

V. Chis ◽

G. Benedek ◽

P. M. Echenique ◽

E. V. Chulkov

Keyword(s):

Orbit Coupling ◽

Spin Orbit Coupling ◽

Spin Orbit ◽

Phonon Interaction ◽

Electron Phonon Interaction

The role of electron–phonon interaction on the transport properties of graphene based nano-devices

Physica B Condensed Matter ◽

10.1016/j.physb.2014.04.034 ◽

2014 ◽

Vol 446 ◽

pp. 85-91 ◽

Cited By ~ 16

Author(s):

A. Mogulkoc ◽

M. Modarresi ◽

B.S. Kandemir ◽

M.R. Roknabadi ◽

N. Shahtahmasebi ◽

...

Keyword(s):

Transport Properties ◽

Phonon Interaction ◽

Electron Phonon Interaction

ROLE OF THE ELECTRON–PHONON INTERACTION ON THE SPECTRAL DENSITY AND PSEUDOGAP IN CUPRATES

International Journal of Modern Physics B ◽

10.1142/s0217979202011184 ◽

2002 ◽

Vol 16 (23) ◽

pp. 3465-3471

Author(s):

I. CHAUDHURI ◽

S. K. GHATAK

Keyword(s):

Critical Temperature ◽

Spectral Density ◽

Low Energy ◽

Phonon Interaction ◽

Energy Excitation ◽

Peak Structure ◽

Electronic Model ◽

Jahn Teller

The pseudogap structure in low energy excitation in cuprates appears below a temperature and the spectral density exhibits strong wave-vector dependence. An electronic model that emphasized the coupling of carrier in Cu-O with phonon is examined for pseudogap. The electron–phonon interaction originates from the modulation of on-site and hopping energy and leads to spontaneous Jahn–Teller-like distortion and pseudogap below a critical temperature. At low temperature the spectral density has two-peak structure about the Fermi level for all k along Γ-M whereas such structure exists along Γ-X for small k only. The magnitude of pseudogap shows strong k-dependence — maximum along Γ-M and vanishes along Γ-X. These features emphasize the role of electron–phonon interaction in formation of pseudogap.