Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ferromagnetism in multi--band Hubbard models: From weak to strong
  Coulomb repulsion   We propose a new mechanism which can lead to ferromagnetism in Hubbard models
containing triangles with different on-site energies. It is based on an
effective Hamiltonian that we derive in the strong coupling limit. Considering
a one-dimensional realization of the model, we show that in the quarter-filled,
insulating case the ground-state is actually ferromagnetic in a very large
parameter range going from Tasaki's flat-band limit to the strong coupling
limit of the effective Hamiltonian. This result has been obtained using a
variety of analytical and numerical techniques. Finally, the same results are
shown to apply away from quarter-filling, in the metallic case.

19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex