A model for paramagnetic Fermi systems

We develop a model for paramagnetic Fermi liquids. This model has both direct and induced interactions, the latter including both density-density and current-current response. The direct interactions are chosen to reproduce the Fermi liquid parametersF ₀ ^s ,F ₀ ^a ,F ₁ ^s and to satisfy the forward scattering sum rule. TheF ₁ ^a andF ₁ ^s,a for1>1 are determined self-consistently by the induced interactions; they are checked against experimental determinations. The model is applied in detail to liquid³He, using data from spin-echo experiments, sound attenuation, and the velocities of first and zero sound. Consistency with experiments gives definite preferences for values ofm*. The model is also applied to paramagnetic metals. Arguments are given that this model should provide a basis for calculating effects of magnetic fields.