TITLE:
A Study of Superconducting La2CuO4 via Generalized BCS Equations Incorporating Chemical Potential
AUTHORS:
G. P. Malik, V. S. Varma
KEYWORDS:
Generalized BCS Equations, Chemical Potential, Two-Phonon Exchange Mechanism, Structure of the Unit Cell of LCO, Gap-to-Tc Ratio, Effective Mass of Electrons, Number Densities of Charge Carriers
JOURNAL NAME:
World Journal of Condensed Matter Physics,
Vol.5 No.3,
August
5,
2015
ABSTRACT: We address the Tc (s) and multiple gaps of La2CuO4 (LCO) via generalized BCS equations incorporating chemical potential. Appealing to the structure of the unit cell of LCO, which comprises sub- lattices with LaO and OLa layers and brings into play two Debye temperatures, the concept of itinerancy of electrons, and an insight provided by Tacon et al.’s recent experimental work concerned with YBa2Cu3O6.6 which reveals that very large electron-phonon coupling can occur in a very narrow region of phonon wavelengths, we are enabled to account for all values of its gap-to-Tc ratio (2Δ0/kBTc), i.e., 4.3, 7.1, ≈8 and 9.3, which were reported by Bednorz and Müller in their Nobel lecture. Our study predicts carrier concentrations corresponding to these gap values to lie in the range 1.3 × 1021 - 5.6 × 1021 cm-3, and values of 0.27 - 0.29 and 1.12 for the gap-to-Tc ratios of the smaller gaps.