Electron correlations in the Hubbard model on the planar pyrochlore lattice

Abstract

We investigate the two-dimensional Hubbard model on the planar pyrochlore lattice at half filling. By means of variational Monte Carlo simulations including nearest neighbor doublon-holon correlations as well as onsite correlations, we discuss how the semi-metallic state is stabilized at zero temperature. The possibility of the plaquette ordered state is also addressed in the framework of our treatment. © 2007 Elsevier B.V. All rights reserved.