14,819 research outputs found
Spin-charge-orbital ordering on triangle-based lattices
We investigate the ground-state property of an e_g-orbital Hubbard model at
quarter filling on a zigzag chain by exploiting the density matrix
renormalization group method. When two orbitals are degenerate, the zigzag
chain is decoupled to a doble-chain spin system to suppress the spin
frustration due to the spatial anisotropy of the occupied orbital. On the other
hand, when the level splitting is increased and the orbital anisotropy
disappears, a characteristic change in the spin incommnsurability is observed
due to the revival of the spin frustration.Comment: 2 pages, 1 figure, Proceedings of SCES'05 (July 26-30, 2005, Vienna
Spin-orbital gap of multiorbital antiferromagnet
In order to discuss the spin-gap formation in a multiorbital system, we
analyze an e_g-orbital Hubbard model on a geometrically frustrated zigzag chain
by using a density-matrix renormalization group method. Due to the appearance
of a ferro-orbital arrangement, the system is regarded as a one-orbital system,
while the degree of spin frustration is controlled by the spatial anisotropy of
the orbital. In the region of strong spin frustration, we observe a finite
energy gap between ground and first-excited states, which should be called a
spin-orbital gap. The physical meaning is clarified by an effective Heisenberg
spin model including correctly the effect of the orbital arrangement influenced
by the spin excitation.Comment: 8 pages, 6 figures, extended versio
Stripe Charge Ordering in Triangular-Lattice Systems
We investigate the ground-state properties of a t2g-orbital Hubbard model on
a triangular lattice at electron density 5.5 by using numerical techniques.
There appear 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 arrangement. It is found that charge stripes stabilized by the
nearest-neighbor Coulomb interaction consist 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.Comment: 2 pages, 2 figures, Proceedings of LT24 (August 10-17, 2005, Orlando
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