The density of hole states for the strongly correlated nearly-half-filled Hubbard model on d-dimensional hypercubic lattices is studied using the moment-expansion method of Brinkman and Rice. Analysis of the extended series suggests that the density of hole states, for antiferromagnetic and random electron spin configurations, has an essential singularity inside the ferromagnetic band edges for d=2, 3, 4, and 5 with characteristic exponents 0.50 and 0.39, respectively. In all cases there is a distinctive narrowing of the spectrum, which becomes more pronounced for larger d. For the dimensionalities studied, the antiferromagnetic case gave the narrowest spectra.

• Received 29 May 1990

DOI:https://doi.org/10.1103/PhysRevB.42.8431