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Onishi, Hiroaki; Hotta, Takashi
AIP Conference Proceedings 850, p.1075 - 1076, 2006/09
We investigate the ground-state property of a 
-orbital Hubbard model on a triangular lattice at electron density 5.5 by using numerical techniques. There appears several types of paramagnetic phases, but we observe in common that one or two orbitals among three orbitals become relevant due to the effect of orbital ordering. It is found that charge stripe stabilized by the nearest-neighbor Coulomb interaction consists of antiferromagnetic/ferro-orbital chains for small Hund's coupling, while there occurs stripe charge ordering with ferromagnetic/antiferro-orbital chains for large Hund's coupling.
-orbital Hubbard modelXavier, J. C.*; Onishi, Hiroaki; Hotta, Takashi; Dagotto, E.*
Physical Review B, 73(1), p.014405_1 - 014405_9, 2006/01
Times Cited Count：9 Percentile：41.49(Materials Science, Multidisciplinary)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.
