https://doi.org/10.1140/epjb/e2005-00080-0
Ferromagnetism in a hard-core boson model
1
Physics Department, University of Wuppertal, 42097 Wuppertal,
Germany
2
Institute for Advanced Studies in Basic Sciences,
Zanjan 45195-159, Iran
3
Physics Department, University of Cologne, 50937 Köln, Germany
Corresponding author: a fledderj@physik.uni-wuppertal.de
Received:
18
November
2004
Revised:
7
January
2005
Published online:
30
March
2005
The problem of ferromagnetism – associated with a ground state with maximal total spin – is discussed in the framework of a hard-core model, which forbids the occupancy at each site with more than one particle. It is shown that the emergence of ferromagnetism on finite square lattices crucially depends on the statistics of the particles. Fermions (electrons) lead to the well-known instabilities for finite hole densities, whereas for bosons (with spin) ferromagnetism appears to be stable for all hole densities.
PACS: 71.10.Fd – Lattice fermion models (Hubbard model, etc.) / 71.27.+a – Strongly correlated electron systems; heavy fermions / 75.10.Jm – Quantized spin models
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005
