Anisotropic Electron Coupling as a Phenomenological Model for High-Temperature Superconductors

摘要

A three-dimensional weak coupling BCS model with an {it anisotropic} pairinginteraction in momentum space is reported. It exhibits an anisotropic gap inaccord with recent experimental observations for high-$T_c$ oxides. The gapratio ${2 Delta / k_B T_c }$ is calculated as function of the anisotropy ratioof the electron pairing. It is found that the mean gap ratio decreases withincreasing anisotropy of the electron pairing, whereas the maximum gap ratioincreases. Assuming a unique strength of the effective electron interaction thetransition temperature turns out to be always larger than in the isotropiccase. The temperature dependence of the gap in the Cu-O plane and along thec-axis of YBaCuO is presented.