SPIN SUSCEPTIBILITY AND MAGNETIC SHORT-RANGE ORDER IN THE HUBBARD-MODEL

The uniform static spin susceptibility in the paraphase of the one-ban d Hubbard model is calculated within a theory of magnetic short-range order (SRO) which extends the four-field slave-boson functional-integr al. approach by the transformation to an effective Ising model and the self-consistent incorporation of SRO at the saddle point. This theory describes a transition from the paraphase without SRO for hole doping s delta > delta(c2) to a paraphase with antiferromagnetic SRO for delt a(c1) < delta < delta(c2). In this region the susceptibility consists of interrelated ''itinerant'' and ''local'' parts and increases upon d oping. The zero-temperature susceptibility exhibits a cusp at delta(c2 ) and reduces to the usual slave-boson result for larger dopings. Usin g the realistic value of the on-site Coulomb repulsion U = 8t for La2- deltaSrdeltaCuO4, the peak position (delta(c2) = 0.26) as well as the doping dependence reasonably agree with low-temperature susceptibility experiments showing a maximum at a hole doping of about 25%.