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Ferromagnetism in the Two Dimensional tt Hubbard Model at the Van Hove Density

R. Hlubina1, S. Sorella1, and F. Guinea2

  • 1INFM, International School for Advanced Studies, Via Beirut 4, I-34014 Trieste, Italy
  • 2Instituto de Ciencia de Materiales, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid, Spain

Phys. Rev. Lett. 78, 1343 – Published 17 February, 1997

DOI: https://doi.org/10.1103/PhysRevLett.78.1343

Abstract

Using an improved version of the projection quantum Monte Carlo technique, we study the square-lattice Hubbard model with nearest-neighbor hopping t and next-nearest-neighbor hopping t by simulation of lattices with up to 20×20 sites. For a given R=2t/t, we consider that filling which leads to a singular density of states of the noninteracting problem. For repulsive interactions, we find an itinerant ferromagnet (antiferromagnet) for R=0.94 ( R=0.2). This is consistent with the prediction of the T-matrix approximation, which sums the most singular set of diagrams.

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