Metal-insulator transition in Mn perovskite compounds

We discuss Mott insulating and metallic phases of a model with eg orbital degeneracy with regard to understanding the physics of Mn perovskite compounds. Quantum Monte Carlo (QMC) and Lanczos diagonalization (LD) results are discussed in this model. To reproduce experimental results on charge gap and Jahn–Teller distortions, we show that a synergy between the strong correlation effects and the Jahn–Teller coupling is important. The incoherent charge dynamics and strong charge fluctuations are characteristic of the metallic phase accompanied with critical enhancement of short-ranged orbital correlation near the insulator.