  We introduce a novel mechanism for itinerant ferromagnetism, based on a
simple two-band model. The model includes an uncorrelated and dispersive band
hybridized with a second band which is narrow and correlated. The simplest
Hamiltonian containing these ingredients is the Periodic Anderson Model (PAM).
Using quantum Monte Carlo and analytical methods, we show that the PAM and an
extension of it contain the new mechanism and exhibit a non-saturated
ferromagnetic ground state in the intermediate valence regime. We propose that
the mechanism, which does not assume an intra atomic Hund's coupling, is
present in both the iron group and in some f electron compounds like
Ce(Rh_{1-x} Ru_x)_3 B_2, La_x Ce_{1-x} Rh_3 B_2 and the uranium
monochalcogenides US, USe, and UTe.

Strongly Correlated Electrons