A Numerical Study of a Disorder-driven 2D Mott Insulator-to-Metal Quantum Phase Transition*

Recent measurements on Sr₃(Ir_1-xRu_x)₂O₇, whose parent compound is a Mott insulator, show that the material undergoes a transition from an antiferromagnetic insulator to an antiferromagnetic metallic phase at sufficiently low temperatures with increasing x. There is experimental evidence that Ru substitution does not dope the system but is only a source of disorder. To model the theoretical nature of disorder generated by the Ru sites, we have studied computationally a two-dimensional Hubbard model in the presence of on-site disorder potentials of a given strength located on a fraction of randomly chosen sites. Using self-consistent mean field calculations, we show that the density of states evolves toward a V-shaped pseudogap at the Fermi energy, in remarkable agreement with experiments. We will also discuss the nature of the local density of states in the different regions of the disordered Mott insulator.