We investigate electron correlations in the two-dimensional Hubbard model on the planar pyrochlore lattice. By means of variational Monte Carlo simulations, we discuss how stable the paramagnetic semi-metallic state is at half-filling. It is found that the increase of the Coulomb interaction induces the first-order transition around U / t ∼ 9, where the magnetically ordered state is more stable than the Mott insulating phase without symmetry breaking.
- Hubbard model
- Planar pyrochlore
- Variational Monte Carlo simulation