We reconsider the problem of a single spin flip in the saturated ferromagnetic state (the Nagaoka state) of the infinite-U Hubbard model for a small (but finite) hole concentration. By studying the ground-state energy and the spin-flip spectral function, we argue that recently proposed Gutzwiller-like variational wave functions are not appropriate for studying this problem in one and two dimensions.

• Received 14 June 1990

DOI:https://doi.org/10.1103/PhysRevB.42.6850