Phase Diagram of the Frustrated Hubbard Model

The Mott-Hubbard metal-insulator transition in the paramagnetic phase of the one-band Hubbard model has long been used to describe similar features in real materials like V₂O₃. In this Letter we investigate the antiferromagnetic phase of this model with frustration. At $T=0$ we find a first-order transition from a paramagnetic metal to an antiferromagnetic insulator. We show that even in the presence of strong magnetic frustration, the paramagnetic metal-insulator transition is hidden inside an extended antiferromagnetic region. This raises the question of whether the one-band Hubbard model with frustration is sufficient to describe the phase diagram of V₂O₃ or similar transition metal oxides even qualitatively.