Field-theoretical approach to Hubbard-like Hamiltonians

Zlatko G. Koinov

Sher Alam, M. Nasir Khan, Jauhar Ali

The Hubbard Hamiltonian and its variants/generalizations continue to dominate the theoretical modelling of important problems such as high temperature superconductivity. In this note we identify the set of relevant operators for the Hubbard Hamiltonian with a magnetic field term.

Stefano Longhi, Giuseppe Della Valle

The hopping dynamics of two fermionic species with different effective masses in the one-dimensional Hubbard model driven by an external field are theoretically investigated. A multiple-time-scale asymptotic analysis of the driven asymmetric Hubbard model shows that a high-frequency bichromatic external field can sustain a low-energy particle bound state (a doublon) in which two fermions of different species occupy nearest-neighbor sites and cotunnel along the lattice. The predictions of the asymptotic analysis are confirmed by direct numerical simulations of the two-particle Hubbard Hamiltonian.

Marius de Leeuw, Vidas Regelskis

Fabian H. L. Eßler, Holger Frahm, Frank Göhmann +2 more

Atsushi Ikawa, Makiko Ozaki

Group theoretically possible spin density waves (SDWs) of the Hubbard model on a triangular lattice are found and classified for ordering vectors q of K and M in the Brillouin zone by finding the maximal subgroups of the symmetry group of the Hamiltonian. It is found that classifications of SDWs with these ordering vectors are reduced to classifications of SDWs on molecules with D 3 and T d symmetries, respectively. From this reduction the authors found two axial-type ASDWs (ASDW) and one plane-type SDW (PSDW) for point K and three ASDWs, two PSDWs and one cubic- (three-dimensional-) type SDW (CSDW) for point M. The standard mean-field Hamiltonians and their invariance groups are listed for each class.