Momentum dependence of effective Coulomb interaction in the magnetism of nickel

Abstract

Lowde and Windsor (1970) have pointed out that good agreement between neutron scattering experiments on Ni and theory is possible if the effective Coulomb interaction is a mildly decreasing function of the momentum. The author presents a variational calculation of the wave vector-dependent susceptibility in the t matrix scheme for the short-ranged one-band model. The scheme satisfies the Ward-Takahashi identities for self-energy and the vertex part. Numerical results are presented assuming an idealised bandstructure for Ni. The computation yields results of the type suggested by experiment. The authors point out the reason why other theories give results which contradict experiment.