THE TRIANGULAR-LATTICE HUBBARD-MODEL - A FRUSTRATED HIGHLY CORRELATEDELECTRON-SYSTEM

We have studied the ground-state properties of the half-filled Hubbard model on the triangular lattice by means of the slave-boson technique . The combined effects of high correlation and frustration in this non -bipartite lattice produce a rich phase diagram, including paramagneti c, commensurate spiral, and linear spin-density-wave phases, as well a s a metal-insulator transition. Unlike previous Hartree-Fock studies o f this model, the slave-boson technique predicts no metallic incommens urate spiral state to be the stable ground state in any region of para meter space.