Author(s)

G. P. Malik^1*, V. S. Varma²

¹Theory Group, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India.
²Planning, Ambedkar University Delhi, Delhi, India.

We address the T_c (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 YBa₂Cu₃O_6.6 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-T_c ratio (2Δ₀/k_BT_c), 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-T_c ratios of the smaller gaps.

Generalized BCS Equations, Chemical Potential, Two-Phonon Exchange Mechanism, Structure of the Unit Cell of LCO, Gap-to-T_c Ratio, Effective Mass of Electrons, Number Densities of Charge Carriers

Malik, G. and Varma, V. (2015) A Study of Superconducting La₂CuO₄ via Generalized BCS Equations Incorporating Chemical Potential. World Journal of Condensed Matter Physics, 5, 148-159. doi: 10.4236/wjcmp.2015.53017.