Ferromagnetism in Hubbard Chains

M. Cuoco, C. Noce and A. Romano Unità I.N.F.M. di Salerno - Dipartimento di Fisica Teorica e S.M.S.A., Università di Salerno, 84081 Baronissi (Salerno), Italy

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We analyze the possible occurrence of ferromagnetism in the Hubbard model, by means of an exact diagonalization study performed on 3- to 8-site chains with periodic boundary conditions. In the case of one hole in the half-filled configuration, we find that the Nagaoka state is reached only in the 3- and in the 4-site case. Ground states characterized by unsaturated ferromagnetism are found when the case of more than one hole is considered.

DOI: 10.12693/APhysPolA.91.387 PACS numbers: 71.10.Fd, 75.10.Lp