Some remarks on pseudogap behavior of nearly antiferromagnetic metals - art. no. 174407

In the antiferromagnetically ordered phase of a metal, gaps open on parts o f the Fermi surface if the Fermi volume is sufficiently large. We discuss s imple qualitative and heuristic arguments under what conditions precursor e ffects, i.e., pseudogaps, are expected in the paramagnetic phase of a metal close to an antiferromagnetic quantum phase transition. At least for weak interactions, we do not expect the formation of pseudogaps in a three-dimen sional material. According to our arguments, the upper critical dimension d (c) for the formation of pseudogaps is d(c) = 2. However, at the present st age we cannot rule out a higher upper critical dimension, 2 less than or eq ual to d(c) less than or equal to 3. We also discuss briefly the role of st atistical interactions in pseudogap phases.