Hubbard model on the anisotropic kagomé lattice: Mott transition and ferrimagnetism

The Mott transition and ferrimagnetism are studied in the Hubbard model on the anisotropic kagomé lattice using the variational cluster approximation, and the phase diagram at half-filling and zero temperature is examined. We find that the ferrimagnetic phase rapidly grows as the geometric frustration is relaxed, and the Mott-insulating phase disappears in moderately frustrated region, indicating that the ferrimagnetic fluctuations stemming from the relaxation of the geometric frustration is enhanced by the electron correlations. In the metallic phase, heavy fermion behavior is observed and mass enhancement factor is computed. Enhancement of effective spatial anisotropy by the electron correlations is also confirmed in moderately frustrated region, and its effect on the heavy fermion behavior is examined.