Dominant antiferromagnetism in the Hubbard model on anisotropic triangular lattices

Abstract: With in mind, we study a half-filled-band Hubbard model on an anisotropic triangular lattice, using an optimization variational Monte Carlo method. As a trial function, we use a state having antiferromagnetic (AF) and -wave singlet gaps simultaneously, and allow for a band renormalization effect in it. It is found that, at a fairy small value of , a first-order conductor-to-AF insulator transition takes place even for remarkably large strength of frustration. In the optimized insulating states, the staggered magnetization is always robust, even for fully frustrated case. Thereby, a regime of robust superconductor as well as of a nonmagnetic insulator vanishes in this wave function. [Copyright &y& Elsevier]