arXiv subjects

A. Messad

Publications and source records attributed to A. Messad.

3 recordsLinked to original sources

arXiv2008

Isotope coefficient of optimally doped high-Tc cuprates

Within the framework of pure BCS(i.e. when the critical temperature is proportional to the Debye temperature), we show that the isotope coefficient is always less than 1/2 and could be extremely small in polyatomic superconductors depending on the chemical formula unit. This finding leads to quantitative explanation of observed values(correct orders of magnitude and sometimes exact numerical values) in optimally doped cuprates, magnesium diboride and alkali-doped fullerenes. Consequently, the smallness of the isotope coefficient is not only compatible with pure electron-phonon interaction, but this is perhaps the rule in polyatomic systems.

cond-mat.supr-con↗

arXiv2007

Oscillation of Tc depending on the number of CuO2 planes in the cuprates

Using the Tc formula given by BCS, together with a shear modulus varying with the numbering of planes, we can demonstrate that Tc oscillates depending on the number of the cuprate planes. The maximum of Tc in these oscillations appears for three planes irrespective of the cuprate family. Comparison with experimental data shows good agreement and suggests that the electron-phonon coupling predominate in the superconductivity of these materials. This model predicts that such oscillations can also occur in many others physical quantities that depend on Tc. The new Tc formula shows interesting prospects towards room temperature superconductors.

cond-mat.supr-con↗

arXiv2007

Tc oscillations in multilayered cuprates superconductors

When combining the BCS expression of Tc with a shear modulus constant model, we can demonstrate that Tc oscillates depending on the number of the cuprate planes and that it reaches its first maximum for three planes. This is in good agreement with experimental data and suggests that the electron- phonon coupling is essential to the superconductivity of the cuprates.

cond-mat.supr-con↗