Spin, charge, and orbital correlations in the one-dimensional -orbital Hubbard model

Xavier, J. C.*; Onishi, Hiroaki  ; Hotta, Takashi; Dagotto, E.*

We present the zero-temperature phase diagram of the one-dimensional -orbital Hubbard model, by using the density-matrix renormalization group and Lanczos techniques. Emphasis is given to the case for the electron density =5, of relevance to Co-based compounds. Several other cases for electron densities between =3 and 6 are also studied. At =5, our results indicate a first-order transition between a paramagnetic (PM) insulator phase and a ferromagnetic (FM) state by tuning the Hund's coupling. The results also suggest a transition from the =5 PM insulator phase to a metallic regime by changing the electron density. The behavior of the spin, charge, and orbital correlation functions in the FM and PM states are discussed.