Self-consistent calculation of spin susceptibility in a two-dimensional tight-binding band

We have calculated the spin susceptibility, as a function of momentum, for a two-dimensional tight-binding band including second-nearest-neighbor coupling in the electron dispersion curves. The effects of charge and spin fluctuations are fully accounted for in a self-consistent way. The renormalization effects due to these interactions are found to be large and momentum dependent. They strongly change the absolute value of the resulting susceptibilities, but their shape in the Brillouin zone is not very different from that obtained in the simple unrenormalized case. The temperature dependence of the susceptibilities is also investigated.