Magnetic Properties of the Hubbard Model on Kagome Stripes

Abstract

We consider the one-orbital N-site repulsive Hubbard model on two kagome like chains, both of which yield a completely dispersionless (flat) one-electron band Using exact many-electron ground states in the subspaces with n <= n(max) (n(max) proportional to N) electrons, we calculate the square of the total spin in the ground state to discuss magnetic properties of the models We have found that although for n < n(max) the ground states contain fully polarized states, there is no finite region of electron densities n/N < 1 (N = N/3 or N = N/5) where ground-state ferromagnetism survives for N -> infinity