Mott transition and ferrimagnetism in the Hubbard model on the anisotropic kagome lattice

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